HARRISBURG, — The Republican State Committee overwhelmingly endorsed Tom Corbett for governor and Pat Toomey for U.S. Senate on Saturday after rejecting conservatives' call for the party to stay neutral in the May 18 primary.

Corbett also revealed to reporters that he has pledged in writing to oppose any tax increase if he is elected governor — a commitment he has previously stopped short of making — but did not mention it in his speech.

Corbett signed the "taxpayer protection pledge" advocated by the Washington-based Americans for Tax Reform earlier this week, according to his campaign manager, Brian Nutt. The pledge promises that he will "oppose and veto any and all efforts to increase taxes."

Nutt said Corbett excluded the pledge from his speech because it was subordinate to his goal of cutting taxes.

In their speeches, Corbett and Toomey painted the Democrats in Harrisburg and Washington as advocates of big spending and big government, while promising to cut taxes, rein in spending and promote policies friendly to the businesses that they said are the only true job creators.

Corbett, the state attorney general best known for his office's ongoing investigation of alleged corruption in the Legislature, said that during his first week as governor he would present lawmakers with a "comprehensive" plan for reforming state government, but offered few details.

"The only jobs that government creates are more tax-funded jobs," Corbett told several hundred committee members and other GOP activists. "Fiscal discipline must be restored in government."

Corbett, 60, of Pittsburgh, faces opposition for the nomination from conservative state Rep. Sam Rohrer of Berks County, who made his presence felt Saturday even though he attracted little support from the state committee.

The Republican nominee for governor would face one of at least four Democrats vying for their party's nomination.

Toomey is opposed in the primary by Peg Luksik, an anti-abortion activist from Johnstown.

If Toomey wins the nomination, he could square off with Arlen Specter again in the general election.

Specter switched parties in April.

He won the Democratic Party's endorsement for a sixth term a week earlier, but still faces a primary challenge from U.S. Rep. Joe Sestak.