Sen. John Warner, R-Va., announced Friday that he will not seek re-election in 2008, concluding a long military and political career that has hoisted him to one of the pre-eminent positions on U.S. foreign policy.

The announcement leaves open a seat that is likely to be hotly contested in the Republican-leaning state that has recently had a tendency to elect Democrats to statewide offices.

Warner chose to make his announcement on the campus of his law school alma mater, The University of Virginia, in Charlottesville.

"All of you have joined me these many years to enable this humble soul to have a magnificent and very rewarding career in the United States Senate," Warner told a crowd gathered there. "My work and service to Virginia as a senator will conclude upon the 6th of January, 2009, when I finish — as the Constitution of the United States (says) on the first Tuesday of a new Congress — my career of then 30 years in the United States Senate."

Warner, a former Navy secretary, said his age was the largest factor in his decision to step aside. He is 80.

Cracking a joke, Warner said a doctor recently told him: "Your 80s are your golden years. Enjoy them. ... On some days, the bells say go full speed ahead. ... And on other days, the whistles say postpone that until next week."

Then, more seriously, he said: "I want to be fair to this wonderful state. ... You have given me my best shot and I am quietly going to step aside and clear the way for others."

He said he also weighed his seniority on the Senate, and his strength as a voice in foreign policy. It wasn't enough for him to decide on another term.

Warner has been a strong voice on Iraq policy, making headlines late in 2006 when he said Iraq was "drifting sideways." It was a bill he sponsored that set the current policy structure that requires Gen. David Petraeus and Ambassador Ryan Crocker to report back to Congress before Sept. 15 on military and political progress in Iraq.

And last week he garnered more attention by calling on President Bush bring home 5,000 troops from Iraq as a calculated move to show Iraq's government that the United States is serious about its call for speedier reforms. Warner on Friday promised to continue to work to end the conflict there.

The 2006 election cycle brought one of the most heated battles in the Democrats' successful bid to win control of both houses of Congress. Sen. Jim Webb, D-Va., launched an upstart campaign against favored former Sen. George Allen.

And in 2005, the only other statewide contest since the 2004 presidential elections, then-Lt. Gov. Tim Kaine, a Democrat, beat Republican Jerry Kilgore in the race for the governor's post. The state, however, favored President Bush in 2004.

Colleagues on both sides of the aisle praised Warner's career as a public servant.

"John Warner has served the people of Virginia with distinction for nearly three decades. Throughout his distinguished career, John has been a leading advocate for the Commonwealth of Virginia, the men and women of our military and the security of our nation," Senate Minority Leader Mitch McConnell of Kentucky said.

"We are all better for having served with him and his Senate family will miss him," McConnell added.

Senate Majority Leader Harry Reid said, "The Senate will be losing a friend and a colleague with the retirement of Sen. John Warner. ... He has been a true gentleman and has served the people of Virginia and our nation with distinction and honor. ... While this is a sad day for the Senate, Senator Warners indelible impact on this institution will not be forgotten."