Sen. Michael Bennet, who is up for reelection in 2016, will donate the money to charity.
The Ohio Republican raised nearly $3 million in the first quarter.
The Maryland Dem is the early favorite to replace retiring Sen. Mikulski.
The Democratic establishment is lining up against P.G. Sittenfeld, Strickland's young primary challenger.
A Chicago newspaper says the Democrat will challenge GOP Sen. Mark Kirk.
Outgoing Dem leader throws support behind ex-Attorney General Catherine Cortez Masto.
Democratic lawmaker said she talked to Reid shortly after he announced he'd retire.
Senate minority leader's retirement will mark end of a long career and open up a top seat.
Eric Holcomb is a former Indiana GOP chairman.
Ron Johnson, a top Democratic target, says student loans are too easy to get.