WASHINGTON - US President Barack Obama's re-election campaign raised more than $45 million in February, increasing its financial haul month-on-month as worries mount that Republicans could outspend Democrats in 2012.

In a statement released on Twitter, Obama's campaign said 348,000 people contributed last month and 105,000 people gave money for the first time.

Nearly 98 percent of the month's contributions were $250 or less, it said.

Obama's campaign and its Democratic allies raised a combined $29.1 million in January. Campaign officials are concerned that outside groups known as Super PACs could outspend Obama in their quest to put a Republican in the White House.