Mississippi Gov. Haley Barbour signed on to aid the fundraising efforts of American Crossroads, the conservative group that is expected to spend millions to boost Republicans in the 2012 cycle.

American Crossroads and Crossroads GPS announced Thursday evening that Barbour joined their team on a volunteer basis, prompting the sister organizations to double their $120 million fundraising goal for the cycle. Their financial goal now stands at more than $240 million.

Barbour’s participation is a major boost to the already cash-flush group. The Mississippi governor boasts access to some of the deepest pockets in the country because of his previous tenure as chairman of both the Republican Governors Association and the Republican National Committee.

“Both Governor Barbour and Karl Rove are prodigious fundraisers and brilliant strategists, and we are honored to have them both engaged with us,” Crossroads President Steven Law said in a statement.

The twin conservative spending groups became major financial players in the 2010 election cycle. Last year, American Crossroads and Crossroads GPS raised $71 million for their political and issues advocacy campaigns, according to a news release.