Control of the Senate is up for grabs on Tuesday, as Democrats look to reverse Republicans' current 51-49 majority in the upper chamber of Congress.
But it won't be easy. If you include Sens. Bernie Sanders (I–Vt.) and Angus King (I–Maine), both of whom caucus with the Democrats, then 26 Senate Democrats are up for re-election, compared to just six Republicans. And 10 of those Democrats represent states President Donald Trump carried in 2016.
Democrats will likely be hard-pressed to flip the two seats they need in order to win a majority. According to FiveThirtyEight, Republicans have an 85 percent chance of staying in control.
Of course, we won't know for sure until all the votes are counted. And whatever does happen will probably depend on the outcomes of these 10 races:
1. Florida: Sen. Bill Nelson (D) looks to fend off Gov. Rick Scott (R).
Both Nelson, who's seeking his fourth term in the Senate, and Scott, a term-limited governor, are familiar faces to Florida voters. Nelson is a relatively moderate liberal who's focusing on things like gun control and health care (specifically protections for patients on Medicare and Medicaid and those with pre-existing conditions). Scott, meanwhile, is touting himself as a problem-solver, citing his past experience as a successful businessman. Scott supports the Second Amendment, though in the aftermath of the Parkland shooting, he signed a gun control bill that raised the minimum age to buy a firearm to 21, and empowered law enforcement to order those deemed a risk to themselves or others to surrender their guns.
Nelson and Scott's faceoff has turned into one of the most hotly contested Senate races in the country. That's not particularly surprising, as Florida is a state Trump won by just 1.2 percentage points two years ago. The candidates have combined to spend at least $33 million on their campaigns. About $27 million of that has come from Scott, including $20 million of his own money. But Nelson holds a slight edge, with a 1.9 percentage point lead in the RealClearPolitics polling average. The nonpartisan Cook Political Report rates the race as a toss-up.
2. Missouri: Sen. Claire McCaskill (D) is in the fight of her life against Josh Hawley (R).
McCaskill has tried to frame herself as a moderate, even going so far as to run a radio ad claiming she's "not one of those crazy Democrats." But it might not be working for the two-term senator. According to CBS News, 55 percent of Missouri voters say she's about as liberal as her Democratic colleagues in Congress. Hawley, on the other hand, bills himself as a "constitutional conservative" who supports Trump's agenda (which is particularly helpful in a state Trump won by more than 18 points).
Hawley was also one of 20 state attorneys general to file a lawsuit against Obamacare. McCaskill has seized on this, claiming Hawley doesn't care about protecting people with pre-existing conditions. Hawley, for his part, says he does opposes all aspects of Obamacare except the pre-existing conditions provision.
If the polls are any indication, this race will come down to the wire. Hawley has a 2-point lead in the RealClearPolitics polling average, though a Fox News poll released Wednesday shows the race is essentially tied. This race, like the one in Florida, is rated as a toss-up by Cook.
3. Arizona: Reps. Martha McSally (R) and Kyrsten Sinema (D) face off in the battle of moderate vs. moderate.
McSally was the early GOP establishment favorite to replace incumbent Sen. Jeff Flake (R–Ariz.). She came through in the Republican primary, easily defeating former state Sen. Kelli Ward and former Maricopa County Sheriff Joe Arpaio. A former Air Force fighter pilot, McSally is running as a moderate, albeit one with an increasingly hardline stance on illegal immigration. Sinema, meanwhile, is also emphasizing border security, though she says she supports "permanent protection" for recipients of the Deferred Action for Childhood Arrival (DACA) program, also called Dreamers.
The other major issue in this race is health care. As The Ringer notes, Sinema played a role in drafting the Affordable Care Act, which is popular in Arizona. Though McSally voted to repeal parts of Obamacare last year, she's talked about her support for a replacement, as well as protections for those with pre-existing conditions.
This race is another toss-up, according to Cook. The RealClearPolitics polling average has Sinema up by 0.7 points, though the latest Fox News poll says things are essentially tied. Sinema may get a boost after Green Party candidate Angela Green, who was reportedly polling at up to 6 percent support, dropped out and endorsed her. If Sinema does pull out the victory, it will be significant, as Arizonians haven't elected a Democrat to the Senate in 30 years.
4. Tennessee: Rep. Marsha Blackburn (R) exchanges blows with former Gov. Phil Bredensen (D).
Things have gotten pretty heated between Blackburn, an outspoken conservative representative, and Bredensen, a somewhat moderate former two-term governor. Outside groups have spent millions of dollars on ads in the race to replace the retiring Sen. Bob Corker (R), many of them negative. As an example of how divisive this race has become, a protester at a Blackburn rally earlier this week yelled out "Marsha Blackburn is a white supremacist" during a moment of silence for the victims of the Pittsburgh synagogue shooting.
Policy-wise, Blackburn mostly supports Trump's agenda, though says she's "not a fan" of his tariffs. Bredensen, meanwhile, touts his record of balancing the budget and cutting "out-of-control spending" during his time as governor. Notably, Bredensen said he would have voted to confirm Brett Kavanaugh to the Supreme Court despite allegations of sexual misconduct against the judge, explaining the evidence "didn't rise to the level" of being disqualifying.
Blackburn appears to have a clear edge just days shy of Nov. 6, with a 6.8-point lead in the RealClearPolitics polling average. Cook, however, still says the race is a toss-up. Even if Blackburn wins, it will likely be by a much smaller margin than Trump, who carried Tennessee by 26 points in 2016.
5. Montana: Tight battle between Sen. Jon Tester (D) and state Auditor Matt Rosendale (R) is further complicated by Libertarian Rick Breckenridge.
Various media reports have portrayed Tester, a two-term Democratic senator, as a down-to-earth politician who tries to focus more on people than on politics. That's understandable, especially in a deep-red state that Trump won by 20 points two years ago. Policy-wise, Tester is something of a moderate—a pro-Second Amendment (at least in theory) Democrat who's supported legislation that would deregulate some banks. Rosendale, meanwhile, is running as a pro-Trump conservative who would vote for the president's federal judicial nominees (Tester voted no on Kavanaugh).
The race is a toss-up, according to Cook, though Tester has a 4.2-point edge in the RealClearPolitics polling average. The contest's tight nature is tougher to predict due to the presence of Libertarian Rick Breckenridge. It's unclear how much support Breckenridge has, but as Reason's Matt Welch reported last month, one poll gave him 4 percent. Contrary to at least one report, Breckenridge is not dropping out, instead telling Reason's Brian Doherty that he supports Rosendale on one particular issue: the shameful use of political "dark money" to send anonymous mailers. If Tester ends up winning, Republicans will still have the chance to scream "SPOILER!"
6. New Jersey: Sen. Bob Menendez (D) may hold on against Bob Hugin (R), but it wasn't supposed to be this tough.
Pundits are divided on just how competitive the race is between Menendez, who's looking to win his third full term in the Senate, and Hugin, a wealthy businessman. The RealClearPolitics polling average gives Menendez a 6.5-point lead, and FiveThirtyEight, which notes the incumbent hasn't trailed in any of the polls, says he has an 87 percent chance of keeping his seat. According to Cook, though, the race is a toss-up.
Regardless, it's surprising that Republicans have even a small shot at flipping a deep-blue state like New Jersey—the same state that went for Clinton by 14 points in 2016. No Republican has won a Senate seat in the state in 46 years. Then again, Hugin isn't a normal Republican. He is not shy about his backing for legalized abortion and LGBT rights, and while he supports border security and opposes sanctuary cities, he does think Dreamers and other illegal immigrants should have a pathway to citizenship.
One thing that certainly hasn't helped Menendez is his 2017 indictment and subsequent trial on federal corruption charges. Menendez has maintained his innocence, and though the case ended in a mistrial, the whole affair might very well have left a bad taste in voters' mouths.
7. Texas: Sen. Ted Cruz (R) might not be as "cool" as Rep. Beto O'Rourke (D), but he'll probably still win.
O'Rourke has mounted a surprisingly competitive campaign against Cruz, an outspoken conservative firebrand and 2016 presidential candidate. Reason's Jacob Sullum has taken note of Cruz's unfortunate lurch to the right on criminal justice reform. O'Rourke, on the other hand, has become something of a media darling thanks to his support of football players who protest police brutality by kneeling during the national anthem.
As Reason's Zuri Davis reported, O'Rourke does hold some problematic views—his support for government intervention over free-market solutions, for instance. But the Texas GOP has chosen to instead attack O'Rourke for being in a band when he was younger, dyeing his hair, and knowing how to skateboard.
Like many Republicans across the country, Cruz has the support of Trump. The president is singing a much different tune than he did during the 2016 election cycle, replacing the nickname "Lyin' Ted" with the moniker "Beautiful Ted." And though Cook still rates the race as a toss-up, Cruz's chances of winning a second term look decent. According to the RealClearPolitics polling average, Cruz is leading O'Rourke by 6.5 points.
8. Indiana: Sen. Joe Donnelly (D) has the edge over former state Rep. Mike Braun (R), but not by much.
Donnelly has a slight 1.2-point edge in the RealClearPolitics polling average for this race, which Cook rates a toss-up. The Democrat, who's seeking a second Senate term, is trying to hold on in a state Trump won by 19 points in 2016. The fact that he's a moderate helps: Donnelly is pro-life, pro-tax cuts (though he voted against the GOP-led tax overhaul, claiming it helped the wealthy at the middle class's expense), pro-border wall, and anti-"radical left." Braun, meanwhile, is very much a pro-Trump conservative these days, though he did vote as a Democrat until 2012. Even on tariffs, which have divided many conservatives, Braun supports the president, though he has said he wants to come up with a better long-term solution that wouldn't hurt Indiana farmers.
But Donnelly and Braun aren't the only candidates with significant support. Libertarian Lucy Brenton is averaging about 5.8 percent in the six independent polls that included her, according to Welch. The Democratic Party is even encouraging conservatives to vote for her. A Democratic campaign mailer sent to conservatives called her an "anti-tax conservative," while claiming Braun "raised Indiana taxes 159 times." The mailer didn't even mention Donnelly. Brenton won't win, but like Breckenridge, she'll likely be labeled a "spoiler" if Donnelly comes away with the victory.
9. North Dakota: Sen. Heidi Heitkamp (D) is probably going to lose to her seat to Rep. Kevin Cramer (R).
Of all the Democratic senators up for re-election this year, Heitkamp is probably the most vulnerable. The one-term Democrat is trailing Cramer by a whopping 11.4 points in the RealClearPolitics polling average. The race leans Republican, according to Cook. So what went wrong for Heitkamp?
It was always going to be tough for her to win re-election, particularly in a state Trump won by nearly 36 points. Heitkamp is a moderate who supports immigration law enforcement. But she did vote against Kavanaugh, and she doesn't think Trump tariffs are helping farmers in her state. Her campaign was also responsible for one of the worst ads this election cycle, in which survivors of sexual assault were outed without their consent. Cramer, meanwhile, agrees with Trump on most issues (Trump's decision to leave the Paris Agreement being one notable exception). Ultimately, Heitkamp probably just won't be able to overcome a very conservative candidate running in a deep-red state.
10. Nevada: For Democrats to take back the Senate, Rep. Jacky Rosen (D) probably needs to unseat Sen. Dean Heller (R).
Like Heitkamp, Heller is the member of his party most likely to lose his Senate seat. Unlike Heitkamp, Heller actually has a 2-point lead in the RealClearPolitics polling average. The race is still a toss-up, according to Cook, and a CNN poll released Wednesday showed Rosen with a 3-point edge.
Heller, who's looking to win a second full term in the Senate, wasn't always the biggest supporter of Trump, though the threat of a primary fight against a challenger from the right changed that. Rosen, meanwhile, has the support of high-profile Democrats like former President Barack Obama, former Vice President Joe Biden, and the democratic socialist Sen. Bernie Sanders (I-Vt.). Rosen has particularly focused on health care, which she believes "is a right, not a privilege," and she's criticized Heller for voting for a partial repeal of Obamacare last year.
As Heller is the only Republican running for re-election in a state Hillary Clinton won in 2016, this is a seat Democrats really need to win.
Honorable mention: New Mexico is the only state with a legitimate three-party race, though Sen. Martin Heinrich (D) is likely to prevail over Mick Rich (R) and Gary Johnson (L).
The results out of New Mexico probably won't be terribly surprising, as Heinrich should easily defeat Rich and Johnson. This race is notable, though, in that Johnson—the state's former governor—will probably garner more votes Tuesday than any other Libertarian in the country.
Trump lost New Mexico by more than 8 points in 2016, and Cook rates the Senate race as "solid" for the Democrats. It's conceivable that if Rich wasn't a factor, Johnson would have a shot at winning, as University of New Mexico political science professor Gabe Sanchez recently told KRQE. But Rich didn't drop out after Johnson announced his candidacy, so the two challengers are likely to split the vote.
Correction: This post originally misspelled Rep. Cramer's last name as "Kramer." I regret the error.