HARRISBURG -- Former Republican Congressman Pat Toomey left no doubt yesterday that he's about to challenge U.S. Sen. Arlen Specter for his seat, and a crowd of 600 conservative Republicans and business supporters gave him a standing ovation.

"It's very likely that very soon I will be a candidate for the U.S. Senate," he said during a 30-minute speech to the Pennsylvania Leadership Conference, which is composed of the Commonwealth Foundation, the Pennsylvania Manufacturers Association, Pennsylvania Right To Work advocates, the Americans for Tax Reform and other conservative groups.

Two or three months ago, he admitted, "I had no plans to run for the Senate, but my mind was changed by three things."

The first: "Dozens and dozens of Pennsylvanians urged me to run," he said.

Then, after Democratic President Barack Obama took office in January, "There was this huge lurch to the left by the federal government," he said, with trillions of dollars being spent to bail out banks and car companies that "our children and grandchildren will have to repay."

Finally, Mr. Toomey said, "Arlen Specter actively supported the Democratic agenda," including being one of only three Republicans to vote for the nearly $800 billion stimulus.

All of this "wouldn't have been possible without the complicity of one man -- Arlen Specter. He voted for all the Wall Street bailouts and the pork-laden spending bills."

After his speech, Mr. Toomey wouldn't say exactly when he would formally declare his candidacy, but the enthusiastic reception he got from people in the crowd made it clear they think he's in the race already.

Nearly everyone at the meeting was wearing a Toomey campaign button.

This will be the second challenge to Mr. Specter by the three-time congressman from the Lehigh Valley, who came within 17,000 votes in 2004 of beating the longtime incumbent.

"He would have won in 2004 except for the foolish endorsement of Specter by [then Republican] Sen. Rick Santorum and [then] President George Bush," griped Don Thomson, head of the Westmoreland County Conservative Coalition. "In 2004, he got 69 percent of the Republican vote in Westmoreland County."

Other strong Toomey backers were Woody and Diane McVicker of Ross, who said they hope a third candidate, Peg Luksik of Johnstown, drops out of the Senate race. She announced her candidacy against Mr. Specter earlier this month.

"Peg is making a big mistake if she doesn't drop out and support Pat," Mr. McVicker said.

"She will fracture the party," agreed his wife.

Mrs. Luksik was present and said she has no intention of dropping out. She seemed a bit miffed at Mr. Toomey, saying he had told her as recently as last month that he wasn't running against Mr. Specter.

As for possible pressure to leave the race so Mr. Toomey could have a one-on-one contest with Mr. Specter, she said, "I don't respond well to pressure. If I think something is the right thing to do, I do it."

Also speaking to the group were the three likely GOP candidates for governor next year -- Attorney General Tom Corbett, U.S. Rep. Jim Gerlach and former U.S. attorney in Philadelphia Patrick Meehan, who prosecuted ex-state Sen. Vincent Fumo on 137 counts of public corruption. Mr. Fumo was convicted on all counts last week.

The three men were asked whom they support for Senate. Mr. Corbett said he's focusing on his own race. Mr. Gerlach also didn't answer, which prompted some boos. Mr. Meehan said he once worked for Mr. Specter and probably would vote for him.

Mr. Meehan said it's necessary to restore the public's faith in state government by ridding it of corruption. He said Mr. Fumo had bragged about "spending other people's money, which is your money, for things like hiring someone to take care of his farm near Harrisburg and to stalk his ex-girlfriend."

Mr. Corbett, who is leading the Bonusgate investigation involving some state legislators and staffers, said, "My exposure of corruption won't end."

Mr. Gerlach said he had voted against the Obama spending bills and had won in years when Democrats such as Gov. Ed Rendell and Mr. Obama did well, showing he can do so in southeastern Pennsylvania even when powerful Democrats run.