HERSHEY, Pa. -- Chester County businessman Steve Welch, Gov. Tom Corbett's chosen candidate for U.S. Senate, received the backing of state Republican Party committee members on Saturday after a tumultuous meeting at the Hershey Lodge that stretched into the afternoon.

While the establishment nod is a show of strength for both Mr. Welch and the governor, it did not considerably alter the primary field. "The only thing this changes is that I'm going to be late for supper," said Armstrong County businessman Tom Smith, referencing the more than four hours it took to reach a result.

Mr. Smith, who has amassed a significant war chest, is expected to mount an aggressive bid against Mr. Welch. Meanwhile, Washington County businessman Tim Burns will be assessing his campaign, political consultant Ray Zaborney said, acknowledging the impact of Mr. Corbett's backing.

State Republicans now head into primary season with an internal battle brewing over who will face off against Democratic U.S. Sen. Bob Casey of Scranton.

Several of the four contenders who also sought the GOP's backing pointed to Mr. Welch's earlier support of both President Barack Obama and Democratic U.S. Rep. Joe Sestak as a fatal flaw.

"I think it's a mistake for our party to nominate a gentleman who is indistinguishable from Barack Obama," said Marc Scaringi, a Harrisburg attorney who garnered a half-dozen votes among the 350 committee members.

Former state Rep. Sam Rohrer, of Berks County, said that "by nominating an Obama supporter, they have unfortunately demonstrated what the people in general have disliked about much of this party."

Mr. Welch responded to that criticism as he accepted the endorsement, describing in his speech how earmarks and corruption scandals soured him on the Grand Old Party.

"Right here in Pennsylvania, hundreds of thousands of people left our party because we failed to govern consistent with our core values. I was one of those people," Mr. Welch said. It was the "extreme agenda" of Democrats in Washington, he continued, that spurred his return to the party.

The candidacy of Mr. Welch, who previously flirted with congressional bids in two southeastern districts, was significantly boosted by the governor's aggressive support. Mr. Corbett declared his selection in the race a little more than a week ago, and drew push-back from party committee members and grassroots activists who preferred an open primary.