WASHINGTON -- Two conservative groups endorsed a primary challenger to Sen. Thad Cochran (R-Miss.) Thursday, one day after Cochran voted for a bipartisan budget deal to reopen the government and raise the debt ceiling. Club For Growth PAC and Senate Conservatives Fund, two groups that opposed the Reid-McConnell bill, endorsed the candidacy of state Sen. Chris McDaniel within minutes of each other.

The endorsements could be a sign of a coming counterattack by conservative interest groups against Republicans who voted for the deal. SCF, Club For Growth and Heritage Action all tried to rally Republicans not to vote for the bill, but it won the support of 87 House Republicans and 27 Senate Republicans. Cochran, 75, has not announced that he's running for reelection in 2014, but he has won by wide margins in deeply conservative Mississippi since 1978.

"Mississippi needs a strong fiscal conservative in the Senate who will fight President Obama and his agenda of higher taxes and bigger government," said Club For Growth President Chris Chocola. "Senator Chris McDaniel is ready to take the fight straight to the liberals in Washington who have led us to $17 trillion in debt. Club members look forward to strongly supporting his candidacy in the primary and general elections next year."

"Chris McDaniel is a constitutional conservative who will fight to stop Obamacare, balance the budget, and get America working again," said Senate Conservatives Fund Executive Director Matt Hoskins.

In response to the endorsements, Cochran spokesman Chris Gallegos said that the senator has indicated that he will announce his 2014 plans later this year. Through June 30, Cochran had raised just $793,153 and had one of the lowest cash-on-hand totals of any senator facing reelection next year, according to reports filed with the Federal Election Commission.

In the 2012 election, the Club for Growth and the Senate Conservatives Fund -- along with SCF's super PAC arm, Senate Conservatives Action -- spent huge sums in Republican primaries. They combined to spend more than $15 million in primaries to challenge incumbents and win open seat races, according to Federal Election Commission documents.

The spending was fueled by the Supreme Court's 2010 Citizens United decision, which freed corporations, unions and, through a subsequent lower court ruling, individuals to spend unlimited sums on independent political activity. Anti-incumbent conservative groups took huge advantage of the decision, increasing their primary campaign spending in 2012 nearly four-fold over 2010.

The spending by the Club for Growth and Senate Conservatives Fund, as well as by other groups like FreedomWorks, helped defeat Indiana Sen. Richard Lugar in his 2012 primary race and Utah Sen. Robert Bennett in a 2010 convention. The groups also chased Pennsylvania Sen. Arlen Specter out of the Republican Party and propelled Sen. Ted Cruz (R-Texas) to his primary victory over the better-funded Lt. Gov. David Dewhurst.

The Club for Growth has already endorsed a primary challenger to Rep. Mike Simpson (R-Idaho), and Senate Conservatives Fund has blasted Senate Minority Leader Mitch McConnell (R-Ky.) for his role in passing the bill to end the government shutdown and avoid a debt default.

Update: 4:25 p.m. -- The conservative Madison Project also endorsed McDaniel Thursday to defeat Sen. Cochran in a Republican primary election. In a press release, the group blasted Cochran as "one of the biggest wasteful spenders of this generation" and "completely missing in action in the fight against Obamacare."

"Sadly, throughout his 34-year career, Senator Cochran has seldom stood up for conservative values, often voting with Democrats for more taxes, spending increases, abortion funding, gun control, and job-killing regulations," the Madison Project's Daniel Horowitz said in a statement.

The Madison Project was the first independent conservative group to endorse Matt Bevin in his primary challenge against McConnell.

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