There's a somewhat odd notion going around that Republicans have dropped the campaign against Obamacare. The New York Times, for example, reported at the end of last week that, "Republican attacks on the health care law dominated the early months of the campaign, but now have largely receded from view."
That's true only if you're not looking.
Obamacare was the number one issue for Republican Senate races between October 13 and 19, as Jeffrey Anderson points out at The Weekly Standard. Anderson cites research by Kantar Media's Campaign Media Analysis Group indicating that the GOP pumped out almost 12,000 ads on the health law that week. You won't be surprised to learn that they weren't in favor of the law. Obamacare was the top issue for Republican ads the week prior as well, with a similar number of GOP ads in opposition.
It's true that Obamacare is less of an issue, relatively speaking, than it was last year at this time, when the launch and failure of the exchanges dominated the news. It's also true that several Republicans have tripped up trying to talk about the law recently, saying that major components are not connected to or part of the law. Compared with six or eight months ago, Republicans are also probably focusing a little more on general opposition to Obama and less to Obamacare.
But it's not the case that Republicans are avoiding the issue, or that it has mostly disappeared from discussion. To the extent that they are campaigning on or against any particular policy at all, it's opposition to Obamacare.