Did Justice Sandra Day O’Connor intend her resignation letter–taking note of “the integrity of the Court and its role under our Constitutional structure”–as a barely veiled shot at the Bush Administration’s political aims? Wishful thinking, perhaps. But O’Connor’s unusual condition of departure–her resignation effective only upon confirmation of her successor–narrows the President’s political options, forestalling a recess appointment and evoking memories of Earl Warren, who held his seat for a full term after submitting his resignation when President Johnson’s nomination of Abe Fortas collapsed.

With O’Connor’s resignation, President Bush, the Senate and grassroots activists all face choices of the greatest historical consequence, in the face of political calculus whose complexity is hinted at by the religious right’s pre-emptive attack on Alberto Gonzales. The selection of O’Connor’s replacement–and the nomination fight itself–will have immediate fallout for abortion rights (with an important parental-notification case already on next term’s docket), the environment, campaign finance reform, criminal justice–all areas in which O’Connor in recent years demonstrated flexibility and pragmatism. This upcoming confirmation is not only about an as-yet-unknown nominee but also about laying down parameters of possibility within which future nominations and Supreme Court decisions themselves will fall.

It is important not to sentimentalize Justice O’Connor. Her nomination by President Reagan as the first woman on the Supreme Court was a historic marker for succeeding generations of female judges and attorneys, but many of the rulings she wrote or supported on voting rights and affirmative action closed the door on redress of past racial discrimination. On criminal justice, her rulings in the 1980s and into the ’90s helped erect rigid sentencing regimes that now haunt governors and judges alike, not to mention the error-ridden edifice of capital punishment–from which O’Connor, in recent years, hesitantly distanced herself, abandoning executions of the retarded to “evolving standards of decency” while mysteriously voting this year to uphold executions of juveniles.

Yet it fell to O’Connor, along with fellow Reagan appointee Anthony Kennedy and George H. W. Bush appointee David Souter, to complete the unfinished business of Roe v. Wade with Planned Parenthood v. Casey in 1992. Their joint opinion, establishing that “the ability of women to participate equally in the economic and social life of the Nation has been facilitated by their ability to control their reproductive lives,” stands as a hallmark of judicial sanity, and as the Supreme Court’s most firmly persuasive articulation of women’s rights. Beginning with Casey, O’Connor’s opinions began showing a new openness to evolving political consensus, her emergence, in delicate chemistry with Justice Kennedy, as a frequent swing vote in 5-to-4 and 6-to-3 civil rights cases. It’s striking that neither O’Connor nor Kennedy can properly be called the leader of the Court’s centrism–they have seemed at times to rely on each other for critical mass.

Are we doomed to a Neanderthal nominee to replace her? The reality is that in some ways, O’Connor’s resignation could not have come at a worse time for President Bush. In the Senate, Bush has expended his political capital and irritated influential Republicans with the war, with John Bolton, with Social Security reform, with Guantanamo. Historically, Republicans have tended to walk in lockstep on judicial appointments, but some Republican Senators’ patience grew thin in the long haggling over Janice Rogers Brown and Priscilla Owen. The Terri Schiavo case taught all Republicans looking toward a presidential run in 2008 that public indulgence of the religious right is not unlimited, despite the powerful patronage machine Christian conservatives have built in the South and Midwest. The circumstance facing Republicans today is very different from that facing George H.W. Bush in 1991, when he placated a suspicious right by nominating Clarence Thomas. The current President is a lame duck, and his would-be successors–most of them in the Senate–need prochoice moderate voters as much as they need the right’s church buses.

It’s not an exaggeration to say that O’Connor’s resignation poses a conundrum for Republicans. The “values” issues with which evangelical leaders have ginned up forces in recent years–gay marriage, Terri Schiavo, abstinence-only education, on and on–are in a sense only surrogates for reproductive rights, from which the far right has been effectively locked out by Casey and by social consensus. Until now there has been little cost to Bush in currying favor among evangelicals. But replacing O’Connor is different. Corporate interests and libertarian conservatives who count on maintaining GOP dominance in the midterm elections and the next presidential race may grow uneasy with the potential cost of a nomination that polarizes the country around culture wars and particularly abortion.

Not that Democrats enter this fray in fighting trim. Democrats’ acquiescence to the ill-advised compromise on judicial filibusters, while scarcely binding given the extraordinary stakes of this nomination, gives the Administration a rhetorical hammer. While Senate Democrats have maintained admirable discipline through the Bolton spat and the Social Security debate, on a Supreme Court nomination they risk falling prey to the caution-inducing vanity and presidential aspirations of Senators Kerry, Biden, Clinton and Bayh, among others, who fear being labeled obstructionist. At least the top Judiciary Committee Democrat this time around is the solid Patrick Leahy, whose devotion to civil rights and liberties is exceeded only by the personal decency he conveys in hearings.

It would be a mistake to assume that this nominee, whoever she or he turns out to be, will occasion a rerun of the Clarence Thomas confirmation battle. But a few lessons from 1991 bear repeating, all the more so since so many of the tacticians on both sides and senators in front of the cameras are the same. By nominating Thomas to succeed Thurgood Marshall, the first President Bush temporarily but effectively divided the civil rights community. The NAACP and some influential African-American leaders, seduced by Thomas’s exaggerated rags-to-robes biography and fearful of opposing a black nominee, initially closed their eyes to the complete consistency and ideological extremity of Thomas’s writings, allegiances and decisions, as well as to evidence of personal misrepresentation and ethical lapse. Only Anita Hill’s allegations of sexual harassment brought Thomas to the brink of defeat.

The disunity of the civil rights lobby in 1991 is not forgotten by today’s President Bush, who plays the diversity card with greater alacrity than any Republican in history. Unity of the civil rights and civil liberties constituencies will be critical in the politics of the coming confirmation. Whether a nominee is female, African-American or Latino, there can be no sentimental presumption that once on the Court a nominee’s ethnic identity or gender will trump a well-established track record on the far right.

The Thomas nomination also inaugurated the dreary but potent addiction of the far right to portraying itself as victimized even at the moment of seizing power. Thomas, you’ll remember, who had risen in just a decade from obscure Education Department bureaucrat to the highest court appointment in the nation, described Anita Hill’s credible allegations of harassment as “a high-tech lynching” by liberals and the media, and bitterly suggested that he was being punished for refusing to toe the line of African-American orthodoxy. To every hard question of a nominee expect a full-throated reprise of that resentful song, amplified through cable TV, talk radio and the Internet. (Would it be above this White House to float a nominee whom it knows ahead of time to be too extreme for confirmation? Defeat turns into a political plus if it mobilizes the right while depleting the resources of the civil rights lobby.)

Of one thing there is no doubt: The meaning of the Constitution’s advise-and-consent clause will get reinvented with this upcoming Supreme Court nomination. As Senator Kennedy has noted, President Bush has an opportunity to turn back the tempest by considering a consensus nominee. But nothing in the confrontation-drenched biographies of Bush or Karl Rove suggests such a consensus-building course.

Rarely has the Supreme Court been in such delicate ideological balance, and never has a nominee walked into as tightly strategized and well-funded a confirmation fight. This battle will be important not just because of the balance of votes on the Supreme Court bench come October, but for what the whole Court comes to understand about the mainstream American public’s dedication to hard-won civil rights and liberties. Anyone who doubts the importance of laying down markers with this nomination need look no further than the words of our most conservative Presidents’ Supreme Court choices. In the 1992 Casey decision, those three Reagan-Bush appointees–Kennedy, O’Connor and Souter–warned of “profound and unnecessary damage to the Court’s legitimacy” should abortion rights be abolished. That is a political judgment in the highest, best Constitutional sense, and that is why the coming confirmation so thoroughly challenges the White House, Democrats and restive Senate Republicans alike.