By Wendell Marsh
WASHINGTON (Reuters) - Former Virginia Governor Tim Kaine resigned on Tuesday as chairman of the Democratic National Committee to run for a U.S. Senate seat from his state in 2012 as his party strives to retain control of the chamber.
Kaine's announcement sets up a possible marquee matchup with Republican former Virginia governor and senator George Allen, who is seeking his party's nomination for the Senate seat being vacated by retiring one-term Democrat Jim Webb.
The Virginia contest is expected to be one of the highest-profile Senate races in the nation next year.
With President Barack Obama running for re-election in 2012, his fellow Democrats face a tough battle to hold their slender majority in the Senate.
Republicans, who already control the House of Representatives, need to pick up four seats to grab control of the 100-member Senate. Democrats must defend 23 of the 33 Senate seats up for grabs in November 2012, including the one Kaine is seeking.
Kaine announced his decision on his website with a video highlighting his past experience on the local and state level. The video steers clear of emphasizing the national Democratic Party chairman position that he gave up to run for Senate.
"I'm running for the United States Senate because America has big challenges and I'm convinced that Virginia has answers to help strengthen our nation," Kaine said in the video.
"It's going to be a highly competitive, exceptionally expensive race that will probably become the most covered Senate contest in the 2012 cycle," said Larry Sabato, director of the Center for Politics at the University of Virginia.
Allen announced in January he will try to win back his old seat. He was defeated by Webb in 2006. Allen faces a Republican primary battle against Jamie Radtke, a favorite of the conservative Tea Party movement, and possibly others.
Webb announced in February he will not seek re-election.
(Reporting by Wendell Marsh; Editing by Will Dunham)