By Mark Willen, Senior Political Editor June 1, 2009 Dr. No said yes today. Sen. Tom Coburn, the physican turned senator from Oklahoma, announced that he will run for reelection next year to a second term. He had delayed planning and fund raising while he mulled his future, saying he hated being away from home so much. His Republican colleagues had pushed hard for him to run, fearful of having to fight for still another open seat.Coburn, 61, has earned a reputaion as a maverick willing to buck his colleagues, especially on earmarks and other federal spending. No one has stepped forward to challenge him, and he seems a sure bet for reelection. Republicans still have to defend five open seats next year -- in Florida, Kansas, Missouri, New Hampshire and Ohio. Plus incumbent Sen. Jim Bunning in Kentucky faces an uphill battle. Democrats have their own vulnerabilities, including the Illinois seat now held by Sen. Roland Burris. Connecticut Sen. Christopher Dodd is another incumbent in trouble, and the open seat in Delaware could be a problem for Democrats if popular GOP Rep. Michael Castle decides to run. Since Pennsylvania Sen. Arlen Specter switched parties, Democrats have had a 59-40 advantage, with the Minnesota Senate seat yet to be decided by the courts. The state's Supreme Court held oral arguments today. The lower courts have all ruled in favor of Democrat Al Franken over Republican Norm Coleman.