Senate Republican challenger Ron Johnson talks to the media after voting in the town of Oshkosh, Wisconsin November 2, 2010. REUTERS/Allen Fredrickson

WASHINGTON (Reuters) - Three-term Senator Russ Feingold lost his re-election bid in Wisconsin on Tuesday to Republican Ron Johnson, the NBC TV network projected, adding another seat to Republican gains in the chamber.

Feingold, one of the most liberal members of the Senate, had trailed much of the race. He was challenged by Johnson, a businessman, over his support for President Barack Obama’s healthcare overhaul, and over government spending.

Johnson’s win will help Republicans narrow the Democrats’ majority in the Senate and could foreshadow trouble for Obama in his 2012 re-election bid after he won the state in 2008.