Maryland Rep. Chris Van Hollen says he will run for the Senate seat that will be open when Sen. Barbara Mikulski retires.
Van Hollen, a Democrat from the Washington 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.