WE STILL don't know who Barack Obama will choose to fill the Supreme Court vacancy created by David Souter.

But all indications point to a bionically engineered candidate who appeals to all the diverse constituencies that put the first black president into the Oval Office. So if the nomination battle were a horse race, the odds would probably be something along the lines of: female, 2-1; Hispanic, 4-1; female and Hispanic, 3-1; openly gay, 6-1; white male, scratched.

This is the first time in more than a decade and a half that a Democratic president will be asking a majority Democratic Congress to approve his high court pick. The last was Bill Clinton, whose choice of Ruth Bader Ginsburg was graciously handled by both sides of the aisle: She was confirmed by a 96-3 vote.

Don't expect to see those numbers this time around. With a polarized Capitol Hill, it's unlikely Obama's choice will skate by Republican senators who still remember the tactics of Leahy, Kennedy and Biden at the Roberts and Alito confirmation hearings, not to mention the "high-tech lynching" that greeted Clarence Thomas in 1991, in which only 11 out of 57 Dems voted to confirm.

ISUPPOSE, IN some ways, it's payback time. Of course, everyone's going to pretend to play nice and give the president's nominee a fair hearing. But you can't erase years of bitterness and partisanship simply because the power has shifted.

When Minnesota Sen. Amy Klobuchar said last week, "I would hope Republicans give the president the opportunity to put his person on the court with some civility," you had to smile and say, "Amy, Amy, Amy - where have you been for the last two decades!" Democrats routinely threatened filibusters when they didn't like the smell of a GOP nominee, and now they have the audacity to talk about "civility" as if the last few confirmation hearings were tea dances.

President Obama should get exactly the same deference as Bush I and Bush II did. Newly defanged Democrat Arlen Specter is well aware of the slash-and-burn tactics that are applied to unfavored high court nominees.

He led the crusade against Robert Bork in the 1980s and, switching sides, defended Clarence

Thomas against Anita's Hill of selective memories. It isn't pretty, but it's legitimate when a lifetime appointment is on the line.

So if Obama chooses someone who tilts too far to the left, he can probably expect

a fight.

And if he insists on making race, sex or ethnicity important criteria, he'd better make sure his nominee has the brilliance to go with it. Diversity for diversity's sake does a disservice to both the favored group and those excluded because they don't have the right labels.

Let's look at some of the handicapped favorites. So far, only one man has been mentioned. That would be Deval Patrick, Obama's governor buddy from Massachusetts. Patrick is the Bay State's first African-American governor, so that's a plus. But he also played a role in the dust-up over plagiarism during the campaign when Obama was accused of using Patrick's words without attribution. And his governorship has been at least mildly disappointing, even to his fans.

Among the women, there's a wide range of choices, all on the far left end of the spectrum.

Let's start with Elena Kagan, the new solicitor general who, as dean of Harvard law school, barred the military from recruiting on campus because of its "don't ask, don't tell" policy. She got all sniffy about losing federal funding because of that move, and sued. The Supreme Court rejected her legal arguments.

Then there's Diane Wood of the U.S. Court of Appeals for the 7th Circuit in Chicago, who's distinctly hostile to pro-life groups, and once let the RICO statute be used against peaceful anti-abortion protesters. The Supreme Court reversed that decision, too, recognizing that a statute designed to dismantle the mob shouldn't be used against rosary-toting grannies.

And then there's Sonia Sotomayor, whose backstory (Puerto Rican, raised in the projects, Princeton and Yale) makes her a favorite. Obama could hit the diversity trifecta with this one: female, Hispanic, liberal. But Sotomayor has been criticized by some legal insiders as having an average legal mind. She also thinks judges should take into account their "experiences as women and people of color" when making decisions. (No mention of the Constitution.)

Judging from this pool, it's going to be a helluva horse race. *

Christine M. Flowers is a lawyer.