The lengthening GOP presidential race is allowing Democrats to build a big cash advantage for the fall.

Financial reports filed Tuesday show President Obama, the Democratic National Committee, a joint fundraising committee between the two and the top super PAC supporting the president have more than $115 million in the bank — more than double the $53 million banked by the GOP candidates, their super PACs and the Republican National Committee.

The gap is widening as the GOP nominee remains unclear.

Over the course of February, the combined cash on hand of the GOP candidates, their super PACs and the RNC declined by a few million dollars, while the Democrats added more than $20 million to their campaign kitty.

Many of the Republican candidates and super PACs spent down their funds considerably in February during the run-up to Super Tuesday on March 6. Rick Santorum and his super PAC combined have less than $3 million in the bank, while Newt Gingrich’s campaign had more debt than cash on hand.

Rep. Ron Paul (R-Tex.) saw his fundraising slow to $3.3 million for the month, and the top super PAC supporting him, Endorse Liberty PAC, raised just $207,000 for the quarter.

Romney is the party’s one bright light, as he turned in his second-best month of the race so far in February. But his campaign and super PAC spent more than $24 million for the month, which was about $6 million more than they raised.

One caveat to all of this: These numbers do no include the American Crossroads super PAC, which focuses more on House and Senate contests but has also run anti-Obama advertisements. Republicans have an edge when it comes to the 2012 congressional campaign because of Crossroads.

In addition, the GOP dominance in the super PAC game is likely to help them close the gap pretty quickly once a nominee is chosen.

But for now, Democrats are slowly and steadily building a sizable advantage. And Republicans are using their money to wage a primary campaign in which Obama is a player rather than the focal point.