WASHINGTON (AP) -- The top financiers of a key Republican political organization are throwing their support behind Mitt Romney.

Major donors to the American Crossroads "super" political committee also contributed more than $3 million in February to a Romney-leaning super PAC that has spent millions of dollars on television ads slamming his Republican opponents.

New reports out Tuesday from the Federal Election Commission signal that some important GOP contributors boosted their support for the former Massachusetts governor just days before Super Tuesday primary elections earlier this month.

Super PACs like the pro-Romney group, Restore Our Future, have become major players this election seasons. Others, like American Crossroads, have remained unaligned this primary season but have promised to spend tens of millions of dollars to defeat Democratic President Barack Obama.