Third-term Sen. Byron Dorgan (D-N.D.) dropped a bombshell Tuesday evening when he announced he will retire rather than running for re-election in 2010, ending a political career that began in the 1960s.

The departure of the influential Senator, who chairs the Indian Affairs Committee and serves in leadership as head of the Democratic Policy Committee, gives Republicans a major opportunity to take the seat in the Republican-leaning state. The party had been trying to woo Gov. John Hoeven into challenging Dorgan and this could cement his candidacy.

In a statement, Dorgan said he came to the decision over the holidays. “It is a hard decision to make after thirty years in the Congress, but I believe it is the right time for me to pursue … other interests,” he said.