Coats beat Democratic Rep. Brad Ellsworth and Libertarian Rebecca Sink-Burris for the seat currently held by retiring Democrat Evan Bayh, according to an Associated Press analysis of exit poll data.

The victory for Coats, who left the Senate in 1999, helped Republicans narrow their 59-41 deficit in the Senate and marked the first in more than 50 years that a member of Congress returned to office after working as a lobbyist. It also signaled a shift in Indiana back toward its more Republican roots after the state supported Democrat Barack Obama for president in 2008.

Coats tweeted to his followers on the social networking site Twitter: "Thank you, Indiana!" He planned to address supporters later Tuesday at the Republican Party celebration.

"I have been listening, and I hear you loud and clear," Coats' prepared remarks said.

Ellsworth thanked supporters and staff at a Democratic Party event in Indianapolis.

"We knew it'd be a high climb, and I don't regret one second," Ellsworth said.

He said before the election that he was confident he did all he could to win with the time and resources available. On Tuesday, he said the only thing in his future right now is getting back in good graces with his dog and raking leaves in his yard.

Coats had portrayed Ellsworth as a rubber stamp for liberals in Washington, while Ellsworth spent much of the campaign criticizing Coats as a wealthy D.C. insider who didn't represent Indiana values.

Voters like Indianapolis resident Elizabeth Farr, 29, didn't buy Ellsworth's argument. She said she chose Coats in part because he opposes the federal health care overhaul, and said her vote wasn't affected by his background as a lobbyist.

"Business is business," Farr said. "In the end, he's going to do what's best for Indiana."

But Indianapolis social worker Candace Backer, 51, cast a straight Democratic ticket and noted that Coats has lived in Virginia for years. Coats is renting a home in Indianapolis and has a second home in North Carolina that is for sale.

"Dan Coats doesn't even live in this state, don't get me started on that," Backer said. "That shows you what a red state this is."

While tea party voters initially preferred more conservative candidates in the GOP primary, many ended up supporting Coats simply because he was a Republican who they felt could stand up to Democrats in Washington. More than eight out of 10 people who said they strongly support the tea party movement voted for Coats, according to preliminary exit poll results conducted for The Associated Press.

Coats said he decided to run for the Senate again after growing unhappy with the direction the country was headed. Voters apparently agreed. About three-quarters said they were angry or disappointed with the way the federal government is working, and Coats won a solid majority of both those groups, early exit polls suggested.

"This is a clear directive from Hoosiers," said Coats spokesman Pete Seat. "They want a senator who will stand up as a check and balance against the tax-and-spend policies of President Obama and Speaker (Nancy) Pelosi."

Coats outraised and outspent Ellsworth, taking in $4.4 million during the election cycle compared to Ellsworth's $2.3 million through the Oct. 13 reporting deadline.

Ellsworth entered the race late because Bayh didn't announce his retirement until February. Because of that, Ellsworth was nominated at the state convention instead of going through a primary, which meant he wasn't campaigning until mid-May. The former Vanderburgh County sheriff and two-term congressman from southern Indiana struggled to gain name recognition statewide.

Bayh said Tuesday that when the economy is struggling, the party in power faces an uphill battle.

"It's a difficult set of circumstances," he told supporters at the Democratic Party's event.

National Democrats didn't support Ellsworth's campaign by running ads, though Ellsworth said throughout the campaign that he wasn't worried about a lack of support from the Democratic Senatorial Campaign Committee because national help was never promised.