The NRSC's March haul was about $1.5 million more than it raised during the same month in 2008. The DSCC also had a larger cash advantage over the NRSC at this point in the last presidential cycle than it does in 2012.

Aided by conservative outside groups that have already spent millions of dollars attacking incumbent Democrats, Republicans are aiming to lay the groundwork to flip the four seats they need to regain control of the Senate in November (if President Obama is reelected).

The NRSC has already reserved $25 million in television airtime for the fall in six key states, with plans to purchase more in the future.