While the Republican National Committee thinks it needs to support immigration reform to start winning presidential elections,  Republicans in Congress have reason to think they need to oppose to keep winning elections. Only 35 percent of Republicans support a path to citizenship for illegal immigrants, according to a Washington Post/ ABC News poll. Among conservative Republicans, only 30 percent support it. Despite, say, Florida Sen. Marco Rubio doing a tour of conservative talk radio to pitch his immigration proposal, support among Republicans has actually declined since February. But Republicans don't just have to win over the Republican base. There are many groups within the GOP that are fighting immigration reform, or are ambivalent about it.

The base.

According to the Post/ ABC poll, 60 percent of Republicans oppose a path to citizenship.

The 2007 Crew.

Conservatives who successfully blocked immigration reform in 2007 -- under a Republican president! -- are reanimating their coalition. "The goal is to stoke enough outrage on the right to dissuade wayward Republicans and moderate Democrats from endorsing the measure," Politico's Manu Raju and Anna Palmer report. Though some of the 2007-era lawmakers have left office -- Tom Tancredo is out of a job -- others are promising to fight an immigration bill. Alabama Sen. Jeff Sessions wrote a letter to Senate Judiciary Committee chair Patrick Leahy demanding any immigration proposal take a long time to get through Congress. It was signed by five other GOP senators: Iowa's Chuck Grassley, Utah's Orrin Hatch and Mike Lee, and Texas's John Cornyn and Ted Cruz. Florida's Marco Rubio appeared to concede on this point, saying, "In order to succeed, this process cannot be rushed or done in secret.”

Right-wing think tanks.

Heritage Action, the lobbying arm of the Heritage Foundation, is on the record opposing a comprehensive bill and measures to grant illegal immigrants legal status. "Amnesty, in whatever form it takes, is a non-starter," the group says. The Heritage Foundation will release a report estimating the cost of immigration reform, which will argue that millions of immigrants will get federal benefits, Politico reports. The Center for Immigration Studies will release it's own report claiming each immigrant will cost the government $2,000. Federation for American Immigration Reform and NumbersUSA are rallying. FAIR will bring 50 conservative talk-show hosts and 25 sheriffs to Washington in April to convince Republicans to oppose "amnesty" and demand a more secure border. NumbersUSA is running ads against immigration reform supporters Lindsey Graham and Mark Begich.

Libertarian think tanks. 

Business-friendly libertarian groups might be expected to give Republicans cover to support immigration reform, but they will not. Club for Growth and FreedomWorks are opting out of the immigration debate, Roll Call's David M. Drucker reports. Both groups have threatened to support conservative primary challengers to Republicans who aren't sufficiently conservative on fiscal issues. Both "have no position on the immigration policies currently being debated in the House and Senate, nor do they intend to be active either supporting or opposing the legislation that is expected to emerge," Drucker writes. While Republicans won't have to fear being attacked by these groups, they won't have support from them, either.