TAMPA – One hour before the final evening of the Republican National Convention was set to be gaveled in session, a group of roughly 100 angry and passionate grassroots Republican delegates, most (but not all) of them associated with either the Tea Party or Ron Paul campaign, held a rally/press conference on a balcony of the Tampa Bay Times Forum to express their bitter displeasure about being disenfranchised by controversial rules changes and delegate recognition-processes on Tuesday.

A series of speakers, shouting into a scrum of reporters while delegates held homemade signs saying "GRASSROOTS," made repeated accusations that the Mitt Romney-led establishment abused the process to prevent future bottom-up presidential runs a la Ron Paul.

"We were railroaded. This is the shot heard 'round the world," said Mark Anthony Jones, a delegate from Missouri's 5th district. Echoing many other speakers, Anthony said the pissed-off delegations were going to stand and fight, agitating for mediators to restore the previous caucus rules that activists learned and exploited to punch above their weight in the long run-up to the convention. (For a breakdown of the complicated parliamentary tussles, see Brian Doherty's piece from Tuesday, and my interview with FreedomWorks' Matt Kibbe.) "We are absolutely not leaving this party," Jones said. "This is my party!"

One delegate from Oklahoma warned, "If these rules changes are the way Mitt Romney will govern as president, then he's unfit for the Republican nomination, he's unfit for the presidency." Another speaker said that activist Republicans "will not vote for Mitt Romney if these rules are in place....This will cause Mitt Romney to lose the election."

A delegate from Alaska went so far as describing the Republican National Committee as an "organized crime syndicate," but he was hissed down by the crowd. The general vibe was that the activists are bloodied but unbowed.

After the ruckus, Minnesota delegate Bill Paulsen, a 33-year-old Paul backer who was on the 39-member Rules Committee that made the controversial changes, explained some of the mechanics behind the outrage. "One thing to understand about the power grab is that it bypassed a deliberative four-year process," Paulsen told me. "They're trying to control the process....It's a few insiders in the party who want to have power."

And it's not just about shutting out noisy constitutional conservatives, Paulsen said. "They don't want to see another Ron Paul, but they also don't want to see another Rick Santorum; let's be honest here," he said. Social conservatives, including a loyalist to Pat Robertson, were among the Rules Committee members most opposed to the changes. Paulsen said he received hundreds of angry e-mails from grassroots Republicans after word about the rules-changes leaked, "and these were not Ron Paul supporters."

Another Minnesota delegate, 37-year-old Daniel Lipp, who is running for the state House of Representatives in an overwhelmingly Democratic district, said that the dispute could do tangible damage to Republicans' electoral prospects in November. "If the grassroots gets damaged...we're going to lose a lot of votes."

The protesters were explicitly forbidden from bringing their signs inside the arena, but I saw many tuck them into their pockets. Look for the small yellow signs that say "GRASSROOTS."