In Kansas, Washington groups helped lift Milton Wolf’s long-shot campaign to defeat Senator Pat Roberts, only to see Dr. Wolf’s campaign founder when it emerged that he had posted graphic X-rays of gunshot victims on his Facebook page.
In North Carolina, FreedomWorks backed Greg Brannon, an obstetrician, as the Republican to challenge the embattled Democratic Senator Kay Hagan. In February, a jury found that Mr. Brannon had misled two investors in his start-up company and ordered him to pay at least $250,000 in compensation. On Tuesday, he was defeated by the establishment’s pick, Thom Tillis, North Carolina’s speaker of the House.
And in Mississippi, a clip surfaced from a radio show in which State Senator Chris McDaniel, the Tea Party challenger to Senator Thad Cochran, riffed on picking up Mexican women by calling them “mamacitas.”
“This guy’s been elected for over five years as a state elected official. That matters,” said Chris Chocola, president of Club for Growth, which stood by its investment in Mr. McDaniel. “I would ask the Cochran folks, ‘If this is so inappropriate, then how come you don’t use it’?” in the campaign in Mississippi?
These issues, particularly the challenges to sitting senators, have unnerved many of the faithful. “They strayed from their plan,” said Victor Mavar, an 87-year-old retired seafood processor from Biloxi, Miss., who said he was a “charter member” of the Club for Growth but wrote a letter to Mr. Chocola to withdraw his support because it had targeted Senator Cochran.
The groups, he said, should focus on taking out Democrats, not fellow Republicans. Senator Cochran, he said, “is honest, he is truthful we’re not going to give him up.”
Republican leaders in Washington hope Mr. Mavar’s view is widely held as they move to starve groups like the Senate Conservatives Fund of contributions.
Speaker John A. Boehner of Ohio and Mr. McConnell, the Senate Republican leader, have vowed to bring about the groups’ demise in the 2014 campaign. Privately, Republican leaders have pointed to possible financial mismanagement and poor candidate vetting to raise doubts among the groups’ small circle of donors.
The Senate Conservatives Fund and its adjunct, Senate Conservatives Action, for example, have raised $12.6 million in this campaign cycle but spent only $4.9 million on the candidates they endorsed. Operating expenditures topped $7.4 million.