In South Carolina, Republican Sen. Lindsey Graham has been attacked in television ads for his support of immigration reform.

In Tennessee, GOP Sen. Lamar Alexander is ducking criticism from Tea Party groups that his overall voting record is too moderate.

Kentucky’s Mitch McConnell, the Senate Republican leader, faces angry conservatives in his state for not joining an effort by some in his party to block the federal budget unless it defunds Obamacare.

For these Republicans, the only uniting factor is that the criticism is coming from their own party. The reasons they are under attack vary from one group to the next.

In South Carolina, television ads began airing in February that sharply criticize Graham for supporting the Senate’s comprehensive immigration reform bill, which pairs new border security measures with instant legalization and a pathway to citizenship for 11 million people now living here illegally.

The campaign against Graham has been waged by NumbersUSA, a group that opposes the Senate bill and seeks to limit immigration.

It’s a move few Republican groups have followed partly because they lack an internal consensus on how to move forward on immigration reform.

“Our members don’t agree on it,” said Barney Keller, a spokesman for the conservative Club for Growth, a political action committee that helped launch Sen. Ted Cruz’s 2012 campaign. “Our members all agree on our stances on taxes, spending, defunding Obamacare and limited government.”

Club For Growth so far has endorsed just one 2014 candidate: Attorney Bryan Smith’s attempt to unseat eight-term Republican moderate Mike Simpson in Idaho’s 2nd District primary. The group has criticized Simpson’s support of the Wall Street bailout and fiscal cliff deal and his votes to raise the debt ceiling.

Graham, meanwhile, has drawn three primary opponents, with his support of immigration reform considered to be the issue that makes him most vulnerable.

“What we tell our activists, in terms of backing a primary opponent, that it’s not always a question of whether you can win, it’s a question of whether you can really inflict some political pain,” NumbersUSA Executive Director Roy Beck told the Washington Examiner. “No incumbent wants to have to deal with a primary. Graham was forewarned.”

Freedomworks, a Tea Party organization that has helped elevate the campaigns of Cruz, R-Texas, and Marco Rubio, R-Fla., is not focused on immigration but rather an effort to defund the Affordable Care Act known as Obamacare.

“I think defunding Obamacare is going to be a rallying cry for the 2014 mid-term election cycle.” Freedomworks spokeswoman Jackie Bodnar told the Examiner.

“Activists want answers from the members of Congress who are not taking a stand to defund a law that’s paid for with money we don’t have, enforced by the IRS, that even the president says isn’t ready for full implementation. And unfortunately, Senator Graham seems to be falling on the side of the White House on this issue.”

Neither Graham nor McConnell has signed onto a letter authored by Sen. Mike Lee, R-Utah, warning Senate Majority Leader Harry Reid, D-Nev., that they will oppose a new government spending bill unless it is stripped of funding for the health care law.

McConnell’s indecision has helped to fuel the campaign of his primary opponent, businessman Matt Bevin, who has challenged McConnell to sign the letter.

Bevin has received the backing of the Madison Project, a group that fights for limited government and is attacking McConnell for his record on a number of legislative issues, most recently his decision to vote to confirm Samantha Power as the U.S. ambassador to the United Nations.

Freedomworks, the Club for Growth and the Senate Conservatives Fund are all considering a move to back Bevin over McConnell.

Alexander, meanwhile, does not have an official primary challenger, but Tennessee Tea Party organizations are looking for a conservative candidate to run against the two-term lawmaker.

Alexander’s recent vote in favor of the Senate immigration bill is just part of the reason behind the opposition. Much of it is fueled by a conservative base that wants more of what Tea Party stars like Cruz and Lee have to offer.

“We see what it’s like to have people in Congress who fight for the people who elected them,” Cunningham said. “We know what it looks like now and I just don’t think people are going to back the kind of mushy moderate Alexander represents.”