CNN:

Sen. John Warner, R-Virginia, said Friday he won't run for re-election.

Warner, 80, has been in the Senate for 29 years.

A former chairman of the Senate Armed Services Committee and former U.S. Navy secretary, he is one of the most respected voices in the Senate on military and national security issues.[..]

Warner was first elected to the Senate in 1978 and has been re-elected four times. In addition to the Armed Services Committee, he is on the Intelligence Committee, the Committee on the Environment and Public Works, and the Committee on Homeland Security and Government Affairs.

Last week, Warner called on President Bush to start the process of bringing U.S. troops home from Iraq in September.

Warner opposed Bush's January decision to send nearly 30,000 additional U.S. troops to Iraq. But he has so far also opposed Democratic efforts to force Bush to start bringing U.S. troops home.

While there's room for some cautious optimism that another Senate seat is in play to increase the Democratic majority (and Virginia's representatives are pretty evenly split between Rs & Ds), having a respected Republican with a really unassailable armed services background backing up our withdrawal stance against the White House is a shame.

UPDATE: Howie says that former Virginia Governor Mark Warner will run and likely win John Warner's seat.