By DICK MORRIS

August 9, 2005 -- Westchester DA Jeanine Pirro is about to formally announce her candidacy for Senate from New York, which will pit her against Hillary in a battle royal. This is just the kind of fight that Sen. Clinton would have hoped to avoid.

While Hillary would have no problem dispatching an opponent like Nixon son-in-law Edward Cox or Yonkers Mayor John Spencer (the two other possible GOP contenders), Pirro presents a real problem.

Jeanine Pirro is pro-choice, pro-gun control, pro-affirmative action, pro-gay-civil unions and pro-immigration. And, of course, she's a woman.

In a sense, Hillary will have to end up running against someone who is quite like herself in her public positions: Except, of course, Pirro is a good old-fashioned anti-tax, anti-crime, tough-on-terror Republican from the suburbs.

Hillary would love to cloak her Senate re-election as a necessity in the face of a determined GOP effort to overturn Roe vs. Wade and to roll back the clock on gun controls. But against Pirro, she will be disarmed of all her best issues. She will have to run on her own record, which is limited at best.

Pirro, on the other hand, can point out that Hillary refuses to say that she will serve out her term if elected — since we all know that the day the returns are in she will start her campaign for president. (Hillary has her own twist on the famous line of Gen. Sherman: "If elected, I refuse to serve").

The Quinnipiac Poll recently found that Hillary beat Pirro by more than 30 percentage points — but in the same poll, 60 percent of the state's voters said that Mrs. Clinton should pledge to serve out her full term if she runs for the Senate.

Jeanine looks weak in the polls right now because she only has about a 30 percent level of real name recognition statewide. But the fact that about one Hillary voter in three says that Mrs. Clinton should promise not to run for president if she seeks re-election to the Senate is an indication that all will not be well for her as she seeks a second term.

If Hillary faced a right-wing opponent, voters would overlook her refusal to promise to serve if elected — but with Pirro, they may come to feel that they have a choice. Recently, Pirro indicated, for example, that she would join the bi-partisan group of 14 senators who promised to save the Senate from destruction by pledging to support reasonable judicial nominees and to refrain from unreasonable filibusters.

And Pirro doesn't need to beat Hillary to wound her. If she finishes less than the 12 points behind Clinton that Rick Lazio managed in the 2000 election, it will be a victory of sorts. Hillary will have some explaining to do to tell why fewer New Yorkers wanted her to be re-elected than voted for her in the first place.

And, at some point, Mrs. Clinton may feel Pirro gaining on them and wonder if it is worth the battle.

It's worth remembering that Hillary did not want Bill to run for re-election for governor of Arkansas in 1990 as he contemplated a race for president in 1992. (Back then she had a better idea: She would run in his place!)

Hillary almost has a lock on the Democratic nomination in 2008 and can build up a massive financial and political lead over all possible rivals. But if she is engaged in a nip-and-tuck battle in New York to keep what she already has, she will have to divert $30 million or $40 million from her presidential race and spend her time in Rochester, rather than in Iowa.

If Pirro posts some early gains, particularly upstate, where it is cheap to do early advertising, Hillary and Bill may read the handwriting on the wall and she may pull out of the race.