Sen. Bayh, right, is throwing his support behind Clinton.
WASHINGTON (CNN) - Sen. Evan Bayh, D-Indiana, who seriously considered his own run for the White House in 2008, will endorse Sen. Hillary Clinton's, D-New York, presidential bid on Monday, said a source close to Clinton.
Bayh is considered a centrist lawmaker on Capitol Hill and once headed the Democratic Leadership Council. Before being elected to the Senate, Bayh served as the governor of his state.
Clinton's campaign has scheduled a 1 p.m. ET news conference to announce the endorsement at a Washington, D.C. hotel.
- CNN Political Editor Mark Preston