Sen. Kent Conrad (D-ND) will not seek re-election in 2012, NPR's Ken Rudin has confirmed.
The Associated Press broke the word about Conrad's decision a short time ago.
First elected to the Senate in 1986, the 62-year-old Conrad is one of the longest-serving Democrats in the chamber -- and not having him on the ballot raises yet another challenge to his party's bid to hold its slim Senate majority.
Last year, North Dakota Democratic Sen. Byron Dorgan opted not to run again. His seat has been filled by Republican John Hoeven.
Update at 10:37 a.m. ET. Ken just filed a report for the NPR newscast:
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"Conrad, the chairman of the Senate Budget Committee, said in a statement that it was more important that he 'spend my time and energy' trying to focus on solving the nation's budget woes than be distracted by another campaign. ... One other senator, Kay Bailey Hutchison, a Texas Republican, has announced her retirement for 2012. With 23 Democratic and just 10 Republican seats up next year, the GOP is optimistic about gaining control of the Senate."