COLUMBUS, Ind. -- Sixth District Republican Rep. Mike Pence said Tuesday that he won't run against Sen. Evan Bayh and will continue to represent his eastern Indiana district.

Pence had been rumored as a challenger to Bayh, who Republicans think is vulnerable as he seeks re-election this year, 6News' Norman Cox reported.

Pence spelled out the reasons for his decision in a posting on his Facebook page.

"I am staying for two reasons -- first because I have been given the responsibility to shape the Republican comeback as a member of the House Republican leadership and, second, because I believe Republicans will win back the majority in the House of Representatives in 2010," Pence's posting said.

During an appearance on MSNBC last week, Pence did nothing to downplay a possible challenge to Bayh, and he hasn't ruled out aspirations to higher offices.

"I hope that God will someday permit me to perform some wider service to the people of Indiana and the country," Pence said on Facebook.

The Rasmussen Poll, out on Monday, showed Pence leading Bayh by three points.

But Bill Blomquist, a professor of political science at Indiana University Purdue University-Indianapolis, said despite those optimistic numbers, Pence may still have been scared off by all the campaign money Bayh has stashed away.

"It's still tough to take on an incumbent senator with $12 million in the bank," he said.

Pence is currently in his fifth term in the House, is a leading conservative and is chairman of the House Republican Conference. His name has begun to surface as a potential presidential candidate in 2012.

Four Republicans have already said they will run against Bayh this year. Former Republican Rep. John Hostettler, state Sen. Marlin Stutzman of Howe, Richmond financial adviser Don Bates Jr. and Fishers businessman Richard Behney are all seeking the U.S. Senate seat.

State Republican spokesman Trevor Foughty said it's unlikely anyone else would add their name to the list of candidates at this late of date.