That's part of the calculation in challenging Republican Sen. Lamar Alexander in Tennessee, where no Democrats hold statewide office, said Michael Leahy, a Republican activist. State Rep. Joe Carr announced in August he would run against Alexander in next year's primary.
Leahy is helping to organize volunteers to knock on doors tomorrow in the state and urge voters to protest Alexander's support for ending the Washington impasse by backing Carr.
"Whoever wins the primary in Tennessee is going to sail to victory," Leahy said in an interview. "Democrats are anemic here."
In addition to Cochran and Alexander, Republican senators who supported the agreement to re-open the government and face primary challenges include Minority Leader Mitch McConnell of Kentucky and Lindsey Graham of South Carolina.
"The strategy of primarying people like Thad Cochran is more of the same and it means more Senate minorities in the future," said David French, the top lobbyist in Washington for the National Retail Federation. "I question the judgment there."
French said the federation would back candidates in Republican primaries. Neither he nor Reed would specify which incumbents they'd support.
"There are incumbent Republicans who are on the wrong side of some of these issues," said French, whose organization spent more than $300,000 on races in 2012. "There are definitely some incumbent Republicans we're not going to support again."
Joining the Senate Conservatives Fund in backing McDaniel's primary challenge of Cochran is the Club for Growth, another tea party ally. The group's super political action committee, Club for Growth Action, spent $17.9 million on federal races in 2012, according to the Center for Responsive Politics.
Senate Conservatives Fund spent $15.9 million in 2012 and $3.9 million so far on 2014 campaigns. The group, a political action committee founded by former South Carolina Republican Senator Jim DeMint, backed Republicans Rand Paul in Kentucky in 2010 and Ted Cruz in Texas in 2012 as each won Senate bids. McDaniel is the group's first endorsement in the 2014 elections.