HE never promised them the Rose Garden. But that’s where America’s self-appointed defenders of family values had expected President Bush to take his latest stand against same-sex marriage last week. In the end, without explanation, the event was shunted off to a nondescript auditorium in the Executive Office Building, where the president spoke for a scant 10 minutes at the non-prime-time hour of 1:45 p.m. The subtext was clear: he was embarrassed to be there, a constitutional amendment “protecting” marriage was a loser, and he feared being branded a bigot. “As this debate goes forward, every American deserves to be treated with tolerance and respect and dignity,” Mr. Bush said.

That debate died on the floor of the Senate less than 48 hours later, when the amendment went down to an even worse defeat than expected. Washington instantly codified the moral: a desperate president at rock bottom in the polls went through the motions of a cynical and transparent charade to rally his base in an election year. Nothing was gained — even the president of the Family Policy Network branded Mr. Bush’s pandering a ruse — and no harm was done.

Except to gay people. That’s why the president went out of his way to talk about “tolerance” at this rally, bizarrely held on the widely marked 25th anniversary of the first mention of an AIDS diagnosis in a federal report. Mr. Bush knew very well that his participation in this tired political stunt, while certain to have no effect on the Constitution, could harm innocent Americans.

When young people hear repeatedly that gay couples aspiring to marital commitment are “undermining the moral fabric of the country, that stuff doesn’t wash off,” says Matt Foreman of the National Gay and Lesbian Task Force. Most concretely, the Washington ruckus trickles down into sweeping assaults on gay partners’ employee benefits and parental rights at the state level, as exemplified by a broadly worded referendum on the Virginia ballot this fall outlawing any kind of civil union. Had Mr. Bush really believed that his words had no consequences, he would have spoken in broad daylight at the White House and without any defensive touchy-feely bromides about “tolerance.”

Mr. Bush prides himself on being tolerant — and has hundreds of photos of himself posing with black schoolkids to prove it. But his latest marriage maneuver is yet another example of how his presidency has been an enabler of bigots, and not just those of the “pro-family” breed.

The stars are in alignment for a new national orgy of rancor because Americans are angry. The government has failed to alleviate gas prices, the economic anxieties of globalization or turmoil in Iraq. Two-thirds of Americans believe their country is on the wrong track. The historical response to that plight is a witch hunt for scapegoats on whom we can project our rage and impotence. Gay people, though traditionally handy for that role, aren’t the surefire scapegoats they once were; support for a constitutional marriage amendment, ABC News found, fell to 42 percent just before the Senate vote. Hence the rise of a juicier target: Hispanics. They are the new gays, the foremost political piñata in the election year of 2006.

As has not been the case with gay civil rights, Mr. Bush has taken a humane view of immigration reform throughout his political career. Some of this is self-interest; he wants to cater to his business backers’ hunger for cheap labor and Karl Rove’s hunger for Hispanic voters. But Mr. Bush has always celebrated and promoted immigrants and never demonized them — at least in Texas. In the White House, he sidelined immigration after 9/11, then backed away from a “guest worker” proposal when his party balked in 2004. After bragging about his political capital upon re-election, he squandered it on Iraq and a quixotic campaign to privatize Social Security. Now Congress has acted without him, turning immigration reform into a deadlocked culture war not unlike the marriage amendment. A draconian federal law is unlikely, but the damage has been done: the ugly debate has in itself generated a backlash against a vulnerable minority.

Most Americans who are in favor of stricter border enforcement are not bigots. Far from it. But some politicians and other public figures see an opportunity to foment hate and hysteria for their own profit. They are embracing a nativism and xenophobia that recall the 1920’s, when a State Department warning about an influx of “filthy” and “unassimilable” Jews from Eastern Europe led to the first immigration quotas, or the 1950’s heyday of Operation Wetback, when illegal Mexican workers were hunted down and deported.

“What a repellent spectacle,” the Fox News anchor Brit Hume said when surveying masses of immigrant demonstrators, some of them waving Mexican flags, in April. Hearing of a Spanish version of “The Star-Spangled Banner,” Lamar Alexander, a Republican from Tennessee, introduced a Senate resolution calling for the national anthem to be sung only in English. There was no more point to that gratuitous bit of grandstanding than there was to the D.O.A. marriage amendment. Or more accurately, both had the same point: stirring up animosity against a group that can be branded an enemy of civilization as we know it.

The most pernicious demagogues on immigration often invoke national security as their rationale, but no terrorist has been known to enter the United States from Mexico. Even the arguments about immigrants’ economic impact are sometimes a smokescreen for a baser animus. As John B. Judis of The New Republic documented in his account of Arizona’s combustible immigration politics, the dominant fear in that border state has less to do with immigrants stealing jobs (which are going begging in construction and agriculture) than with their contaminating the culture through “Mexicanization.” It’s the same complaint that’s been leveled against every immigrant group when the country’s in this foul a mood.

That mood was ratcheted up last week by the success of Brian Bilbray’s strategy in winning the suburban San Diego House seat vacated by the jailed Duke Cunningham. Mr. Bilbray, a card-carrying lobbyist, was thought to be potentially vulnerable even in a normally safe Republican district. But by his own account, his campaign took off once he started hitting the single issue of immigration, taking a hard line far to the right of the president who endorsed him. Mr. Bilbray goes so far as to call for the refusal of automatic citizenship to the children of illegal immigrants — a repudiation of the 14th Amendment, enacted after the Civil War to ensure citizenship to everyone born in the United States.

His victorious campaign set a tone likely to be embraced by other Republicans fearful of a rout in 2006. The election year is still young, and we haven’t seen the half of this vitriol yet. Some politicians, like Senator James Inhofe of Oklahoma, are equal-opportunity bigots: when he isn’t calling for the Senate to declare English the national language and demanding that immigrants be quizzed on the Federalist Papers (could he pass?), he is defending marriage by proclaiming that in his family’s “recorded history” there has never been “any kind of homosexual relationship.” (Any bets on how long before someone unearths the Inhofes’ unrecorded history?) Vernon Robinson, a Republican Congressional candidate challenging the Democratic incumbent Brad Miller in North Carolina, has run an ad warning that “if Miller had his way, America would be nothing but one big fiesta for illegal aliens and homosexuals.”

The practitioners of such scare politics know what they’re up to. That’s why they so often share the strange psychological tic of framing their arguments in civil-rights speak. The Minuteman Project, the vigilante brigade stoking fears of an immigration Armageddon, quotes Gandhi on its Web site; its founder, Jim Gilchrist, has referred to his group as “predominantly white Martin Luther Kings.” On a Focus on the Family radio show, James Dobson and the White House press secretary, Tony Snow, positioned the campaign to deny gay civil rights as the moral equivalent of L.B.J.’s campaign to extend civil rights. James Sensenbrenner, the leading House Republican voice on immigration policy, likened those who employ illegal immigrants to “the 19th-century slave masters” that “we had to fight a civil war to get rid of.” For that historical analogy to add up, you’d have to believe that Africans voluntarily sought to immigrate to America to be slaves. Whether Mr. Sensenbrenner is out to insult African-Americans or is merely a fool is a distinction without a difference in this volatile political climate.

Mr. Bush is a lame duck, but he still has a bully pulpit. Here is a cause he has professed to believe in since he first ran for office in Texas, and it’s threatening to boil over in an election year. Imagine if he exercised leadership and called out those who trash immigrants rather than merely mouthing homilies about tolerance and dignity.

Tolerance and dignity are already on life-support in this debate. If the president doesn’t lead, he will have helped relegate Hispanics to the same second-class status he has encouraged for gay Americans. Compassionate conservatism, R.I.P.