Jeanine Pirro's (search) fledgling campaign for the Republican nomination to take on Sen. Hillary Rodham Clinton next year was hit from two sides Thursday as she lost out on a county chairman's backing and one of her rivals trotted out a TV ad mocking her GOP credentials.

"She's not running to beat Hillary Clinton (search), she running to be Hillary Clinton," said the 30-second television spot appearing on former Yonkers Mayor John Spencer's (search) Web site — http://www.joinspencer.com — on Thursday.

Spencer's ad, which strategist John McLaughlin said would begin airing next week on cable channels across the state, notes that Pirro and Clinton both support abortion and gay rights, and gun-control legislation.

Spencer and Manhattan lawyer Edward Cox (search), who is also seeking the GOP Senate nomination, have said that Pirro, Westchester County's high-profile district attorney, is too liberal to win the backing of the state Conservative Party. No GOP candidate for statewide office in New York has won without Conservative Party backing since 1974.

A Pirro campaign spokesman did not immediately respond to a request for comment.

While Spencer was unveiling his TV ad, Cox was announcing the backing of Washington County GOP Chairman John Aspland (search).

Aspland said he was opting for Cox, a son-in-law of the late President Richard Nixon, over Pirro because "he's the better of the two leading candidates."

"She's a dynamic speaker and a TV personality kind of person, but I'm looking for somebody who's going to get the job done for upstate and is electable," Aspland said.

The Aspland endorsement was of particular note because his was among the names of 46 county GOP chairmen — out of 62 — appearing on a June 20 letter urging Pirro to run for the nomination.

While Aspland said Thursday he couldn't even remember signing the letter, "at that time I wanted any viable candidate coming forward."

"That was then. This is now," Aspland added.

"She'd make a hell of a candidate for attorney general," the Washington County party leader said.

Meanwhile, Pirro was in Syracuse on Thursday, touring the State Fair on opening day with Gov. George Pataki and picking up the endorsements of state Sen. John DeFrancisco and Onondaga County Executive Nicholas Pirro. Pataki has not endorsed anyone yet. On Wednesday, she had been in Rochester to pick up the backing of Monroe County Executive Maggie Brooks and state Sen. Michael Nozzolio.

Besides Pirro, Cox and Spencer, the GOP Senate nomination is also being sought by a little-known tax attorney from Sullivan County, William Brenner (search).