(AP Photo/Rogelio V. Solis)

American Crossroads, a GOP establishment organization, has decided to shift its political focus almost entirely to the general election and will not be spending money in the likely runoff election to decide the Mississippi Senate nomination that was virtually deadlocked after Tuesday night.

Founded by Karl Rove and other Republican strategists, Crossroads and its non-profit affiliate, Crossroads GPS, had not played an active role in supporting GOP Sen. Thad Cochran’s bid to thwart a primary challenge from state Sen. Chris McDaniel, but the group had been working behind the scenes to boost other pro-Cochran super PACs.

"Other than Alaska, we have completed our work on Senate primaries this cycle and are now focused on general elections. With the Chamber, the NRSC, and a local super PAC already backing Cochran, this is not our fight,” Paul Lindsay, spokesman for Crossroads, said in a statement.

Both Cochran's and McDaniel’s campaigns, after a brutal primary campaign that left both hovering around 49 percent of the vote, are virtually broke as they begin a three-week sprint to the June 24 run-off. That places a high premium on funding from outside conservative groups, which poured millions of dollars into the ad wars that dominated the final weeks of the campaign.

The U.S. Chamber of Commerce, which has had an effective spring in backing more establishment figures in GOP primaries, is expected to continue financing an effort to boost Cochran, as is Mississippi Conservatives, a super PAC founded by longtime operative Henry Barbour.

Those two groups spent a combined $1.5 million on TV ads on behalf of Cochran, according to an analysis of advertising purchases provided to the Washington Post. Cochran spent an additional $1.8 milllion. The National Republican Senatorial Committee pledged to “fully support” Cochran in the runoff, although it remains to be seen if that will finance any ads on his behalf.

But the anti-establishment groups based in Washington neutralized that money with their own ad campaign in what has become something of a last-stand race for those groups. The Club for Growth poured $1.4 million into TV ads backing McDaniel, while groups affiliated with the Senate Conservatives fund spent about $870,000 in the air wars, mostly attacking Cochran. Because these groups have not yet ousted a sitting GOP incumbent in a primary, they are expected to double down in their effort to defeat Cochran in the runoff.

Crossroads would have been a big lift for Cochran, had it decided to join the fray. Instead, the group decided its only remaining focus in the primary season was to continue boosting Dan Sullivan in Alaska, where the former federal prosecutor has emerged as a consensus frontrunner for the GOP nomination with support from establishment groups like Crossroads and the Club for Growth.