Sunday will mark the four-year anniversary of President Obama signing the Affordable Care Act into law -- and Republicans, feeling freshly vindicated, are celebrating with swagger.

“I think the gift from President Obama to Democratic candidates is not a dozen roses, but a bunch of prickly pear cactus they're not going to want to embrace,” National Republican Congressional Committee Chair Greg Walden said during a call with reporters Friday.

Republicans are poised to keep their majority in the House and are increasingly well-positioned to challenge Democrats for the Senate majority -- in part, Republicans say and polls seem to confirm, because of the poor public reception of the president's signature health care law.

Now, as many as 13 Senate races could be in play for Republicans, said Sen. Jerry Moran, R-Kan., chairman of the National Republican Senatorial Committee.

“The map and opportunities have expanded dramatically in a year, in part because of the consequences of Obamacare,” Moran said during the call.

Republicans have grown more optimistic in light of a recent, high-profile test case: the special election in Florida's 13th Congressional District, where Republican David Jolly bested Democrat Alex Sink. During the campaign, Jolly attacked Sink on Obamacare, while Sink adopted Democrats' message that Republicans would reverse the law's positive changes.

Democrats are sticking with that defense for now, and have continued to warn that Republicans are not interested in replacing Obamacare with a better alternative.

“All signs point to Republicans running against Obamacare again in 2014,” Democratic National Committee communications director Mo Elleithee wrote in a memo Friday. “But this year will be a little different -- for the first time they are running to take away benefits that virtually every American who has health care is benefiting from.”

Indeed, Republicans have so far been unable to coalesce around an alternative to replace the Affordable Care Act, although the party has little incentive to propose any concrete policy changes while Republican primary races are in progress.

Democrats, for all of the political risks of discussing the health care law, insist it’s a discussion they want to have.

“The American people have a clear choice in November,” Elleithee added. “That's a debate we're ready -- and eager -- to have.”