In a move that surprised some political observers, Westchester County District Attorney Jeanine Pirro (R) announced Monday that she intends to challenge Sen. Hillary Rodham Clinton (D) in 2006.

“I am running against Hillary Clinton because New York state deserves a Senator who will give her all to the people of New York for a full term, who will not miss votes to campaign in [presidential] primaries,” Pirro said in a statement first reported by The Associated Press.

Pirro, who was widely expected to run for state attorney general, is the third Republican in the race against Clinton, joining former Yonkers Mayor John Spencer and Ed Cox, the son-in-law of late President Richard Nixon.

She is the best known of the three and was encouraged to join the race by a number of Republican operatives in the state, including state GOP chairman Stephen Minarik.

Pirro was re-elected in 2001 to her current post despite ongoing problems surrounding her husband, who at the time was imprisoned as the result of a $1.2 million tax fraud conviction.

Pirro was forced to drop out of the 1986 lieutenant governor’s race due to allegations involving her husband’s business practices. She was first elected district attorney in 1993, the first woman to hold that post. Previously, she served as a county prosecutor for 15 years.

Even so, Pirro faces an uphill contest against the well-funded Clinton, who showed almost $13 million on hand at the end of June.

Recent polling showed Clinton with strong leads over all three Republicans.

Clinton led Pirro 63 percent to 29 percent according to a Quinnipiac survey in the field from July 27 to August 1. Her margin over Cox was 64 percent to 26 percent in the same survey.

“A number of Republicans have announced their intention to run for the Senate,” said Clinton spokesman Howard Wolfson. “While the GOP sorts out its nominating process, Senator Clinton will continue her hard work on behalf of the people of New York.”