By THOMAS BEAUMONT and CHET BROKAW
SIOUX FALLS, S.D. (AP) _ Democratic U.S. Sen. Tim Johnson of South Dakota says he's retiring at the end of his term, acknowledging he remains limited by a recent ``health crisis.''
The 66-year-old said at a news conference that ``my right arm and right leg aren't what they used to be and my speech is not entirely there.''
Appearing in his hometown Tuesday, Johnson made it official he will not seek a fourth term. Lingering effects from a 2006 brain hemorrhage have slowed his speech and caused him to use a motorized scooter.
The move gives Republicans one of their best chances to gain a seat and regain Senate control.
The only announced Republican candidate so far in the GOP-trending state is Mike Rounds, who was governor for two terms after being elected in 2002.
Copyright 2013 The Associated Press