BISMARCK, N.D. -- North Dakota Sen. Byron Dorgan stunned fellow Democrats when he decided not to seek re-election this fall and swung open a race that Republicans are convinced will help the GOP dent the Democrats' fragile majority in the Senate.
Dorgan's announcement Tuesday means Democrats will have to defend open Senate seats in at least four states in what could be a challenging election year. Anti-incumbent sentiment is brewing among voters, and the party in power typically gets blamed for the county's troubles.
North Dakota Republican Gov. John Hoeven -- who has won his last two elections with more than 70 percent of the vote -- appeared ready to jump into the 2010 race. The three-term governor had shrugged off questions about challenging Dorgan, but said Tuesday he was considering a run "very seriously."
"I expect we'll announce our intentions here within a couple of weeks," Hoeven, 52, told The Associated Press.
Dorgan, who was first elected to the Senate in 1992 after serving a dozen years in the House, said he reached the decision after discussing his future with his family over the holidays. Dorgan, 67, said he "began to wrestle with the question of whether making a commitment to serve in the Senate seven more years was the right thing to do."
"Although I still have a passion for public service and enjoy my work in the Senate, I have other interests and I have other things I would like to pursue outside of public life," he said in a statement.
North Dakota Republicans were jubilant, saying they were confident Hoeven would run and could overcome any Democratic challenger in the fall.
"I believe this seals the deal," said Kevin Cramer, a Republican state public service commissioner who is considering running for the U.S. House.
Democrats hold an effective 60-40 majority in the Senate -- enough to break Republican filibusters -- if they and the chamber's two independents, who align themselves with Democrats, stick together.
North Dakota's three-person congressional delegation has been solidly Democratic since Sen. Kent Conrad, D-N.D., defeated incumbent Republican Mark Andrews in 1986. Republicans have held the governorship since 1992 and controlled the state Legislature since 1995.
Dorgan had been preparing for his fourth Senate race for almost two years. He had hired a former aide in 2008 to lay the groundwork for a campaign and raised $3.9 million through last September -- a princely sum in North Dakota politics.
Early polling showed Dorgan trailing Hoeven in a hypothetical contest, and Democrats expected a competitive race if the matchup materialized.
Democratic Rep. Earl Pomeroy is a possible Senate candidate, and Democratic activists believe Heidi Heitkamp, a former Democratic attorney general and tax commissioner, could run. Heitkamp did not respond Tuesday to phone and e-mails seeking comment. She lost to Hoeven in the governor's race in 2000. A Facebook page set up by a Heitkamp supporter collected well over 200 supporters in less than three hours Tuesday night.
Pomeroy issued a statement praising Dorgan's public service but didn't mention whether he planned to run for Senate. A Pomeroy spokeswoman said he was unavailable for comment.
President Barack Obama said in a statement that Dorgan gave "30 years of devoted service to the U.S. Congress" and was a champion for family farmers and praised his work to improve health care on American Indian reservations. Dorgan is chairman of the Senate Indian Affairs Committee.
Conrad said in a statement that Dorgan "produced important and lasting results for North Dakota" and said he expected Dorgan would be in line for a future Cabinet appointment in Obama's administration.
Senate Majority Leader Harry Reid of Nevada was considered in serious trouble, and five-term Sen. Chris Dodd of Connecticut was expected to announce Wednesday that he won't seek re-election, according to officials who would speak only on condition of anonymity ahead of the announcement. The other seats vacated by Democrats are in Delaware and Illinois.
Republicans are defending open seats in Ohio, Florida, Missouri, New Hampshire, Kentucky and Kansas.
Dorgan's decision also could have ramifications for another of Obama's top priorities -- climate and energy legislation.
Representing a large oil and coal-producing state, Dorgan opposes the bill backed by the White House and Democratic leaders that would put a limit on heat-trapping pollution and would allow companies to swap valuable emissions permits. Dorgan instead has pushed an energy bill that would boost renewable energy production and oil drilling.
With no re-election race, Dorgan could become even more of a wild card on the issue.