U.S. Rep. Chris Van Hollen of Maryland says he will run for the Senate seat that will be open when Sen. Barbara Mikulski retires.
Van Hollen, a Democrat from the D.C. suburbs, announced his plans in an email to supporters Wednesday. His email was sent two days after Mikulski announced she would not run for re-election in 2016.
Van Hollen, who has been a congressman since 2003, wrote that a more formal announcement of his Senate bid will come later.
He will be running in what could be a crowded race, with a variety of Democrats considering a run. Rep. John Delaney already has indicated he will explore a Senate run.
Maryland Republicans also are taking an interest in the seat, which Mikulski has held since 1987.
Van Hollen represents Maryland's 8th district, which includes portions of Montgomery County and stretches north to portions of Frederick and Carroll counties.