By LAURIE KELLMAN

Associated Press Writer

WASHINGTON (AP) -- Democratic Sen. Tim Johnson of South Dakota suffered a possible stroke Wednesday and was taken to a hospital, his office said.

If he should be unable to continue to serve, it could halt the scheduled Democratic takeover of the Senate. Democrats won a 51-49 majority in the November election. South Dakota's governor, who would appoint any temporary replacement, is a Republican.

"Senator Tim Johnson was taken to George Washington University Hospital this afternoon suffering from a possible stroke," read a statement from his Senate office. "At this stage, he is undergoing a comprehensive evaluation by the stroke team."

Johnson had become disoriented during a call with reporters, stuttering in response to a question. He appeared to recover, asking if there were any additional questions and then signing off.

If the two-term senator, 59, is unable to serve when the 110th Congress convenes Jan. 4, South Dakota Gov. Mike Rounds would appoint a replacement.

AP-ES-12-13-06 1628EST