It was the worst-kept secret in Virginia, but now it's official: Sen. Mark Warner will not run for governor again.

The popular Democrat announced Tuesday that he'll remain in the Senate, where he has taken on a central role helping negotiate a bipartisan budget deal. Warner promised he would decide whether to seek a second term by Thanksgiving, but most insiders assumed he would not.

"I loved being governor, but I have a different job now -- and it's here, in the United States Senate," Warner said in a long, emotional statement.

The decision was not an easy one for Warner, who said he was asked by both Democrats and Republicans to run. Warner called his time in Richmond "the best job I ever had."

By stepping aside, Warner makes way for Terry McAuliffe to capture the Democratic nomination. McAuliffe, who unsuccessfully ran in 2009 and served as Democratic National Committee chairman, announced his intention to run after the presidential election earlier this month.

With a background in business Republicans respected and progressive social views that attracted Democrats, Warner remains Virginia's most well-liked current officeholder. Had he ran for governor, polls showed he would have won in a landslide over Attorney General Ken Cuccinelli or Lt. Gov. Bill Bolling. both Republicans.

As it stands, McAuliffe holds a slight edge over Cuccinelli and an even smaller one against Bolling, according to Quinnipiac University polling.

Warner served in the governor's mansion from 2002 to 2006. He was elected to the Senate in 2008, handily defeating former Republican Gov. Jim Gilmore with 65 percent of the vote.

In the Senate, Warner has worked in both the "gang of eight" and "gang of six" -- bipartisan coalitions of lawmakers pushing a budget compromise -- often ruffling the feathers of party leadership. He has repeatedly expressed displeasure at the pace of the Senate and its lack of action, and will continue to be a vocal figure during upcoming "fiscal cliff" negotiations.

"At times, it's been frustrating," Warner said. "But I believe this work is important for Virginia, and for our country, and I intend to see it through."