June 25 (Bloomberg) -- American politics is usually a zero- sum game: When one side gains the other loses.

An exception is the current battle to overhaul immigration laws. The bipartisan effort is led by the unlikely duo of President George W. Bush and Senator Edward M. Kennedy. The fate of the legislation, which would grant a pathway for citizenship to 12 million illegal aliens and toughen enforcement of the borders, will be decided by the U.S. Senate this week.

If it passes, there is plenty of credit to share; if it fails both Bush and the Republicans and the Democratic-controlled Congress will be big losers.

Although a majority of the public is in favor of changing a chaotic system that makes a mockery of the law, it won't be easy.

The immigration bashers are winning the demagoguery war. Tom Tancredo, a Republican congressman from Colorado and a presidential candidate, has suggested immigrants come to the country to commit crimes and called Miami a Third World city. Lou Dobbs, a television host on the Cable News Network, has raised the specter of thousands of illegal immigrants spreading leprosy -- demonstrably untrue.

The roots are historic: nativism, or a fear that new arrivals will debase and threaten the American way of life. ``We've been down this road before,'' says Senator Lindsey Graham, the South Carolina Republican and a leading supporter of the comprehensive immigration measure. ``No Catholics, no Jews; the Irish need not apply.''

Profiles in Cowardice

This intimidation has produced profiles in cowardice. Georgia Republican Senators Saxby Chambliss and Johnny Isakson originally backed the compromise immigration measure. After taking heat at home, they retreated.

So have others who should know better. A year ago, former Massachusetts governor and Republican presidential candidate Mitt Romney embraced liberalizing immigration laws; his top policy and economic advisers still do. Yet as candidate Romney appeals to core conservative constituencies, he now rails against the legislation as ``amnesty'' for illegals.

Conversely, rival John McCain's steadfast support for a more rational immigration policy has cost him with Republican primary voters.

Whatever the short-term effects, however, rejecting the immigration overhaul would be a long-term disaster for Republicans. It would deny Bush any domestic legacy, making him the most-failed second-term president in modern American politics. History tells us that would drag down his party in subsequent elections.

Disillusioned Hispanics

It would also imperil Republican prospects for years with Hispanics, the fastest-growing slice of the American electorate. In 2006, surveys suggest Republicans got less than 30 percent of the Hispanic vote, a drop of about 10 points that cost them a half-dozen House seats and several in the Senate.

This reflects disillusionment with the anti-immigrant posture of prominent Republicans. Party Chairman Mel Martinez, a Florida senator and himself an immigrant from Cuba, warns it may be ominous for next year: ``If we get the same type of Hispanic support in the next election cycle that we did in the last, there is no way we can elect a Republican president.''

Any doubters should look to California. In 1994, Republican Governor Pete Wilson, worried about a tough re-election campaign, played the immigration-bashing card.

Pyrrhic Victory

He won that year, but ever since, Republicans have come up short in the state because of defections by Hispanic voters. The party, which had carried the state in six of the previous seven presidential elections, has been trounced in the last three contests. Democrats have increased their margins in Congress and only lost the governorship through a quirk when Arnold Schwarzenegger won a special election.

Jerry Warren, who was the editor of the San Diego Union in 1994 and before that a press secretary for Richard Nixon, sees the party today following a similarly destructive path nationally. Senator Graham agrees: ``This is Pete Wilson on steroids.''

Great, say some top Democratic politicians, let's sit back and watch Republicans self-destruct, elect a Democratic president next year and then enact a better immigration-reform bill.

That kind of thinking is as myopic as the immigration bashers. It only gets tougher with each passing year to do anything on immigration, and without the cover of Bush's courageous support, even fewer Republicans are likely to help two years from now.

The Biggest Losers

Congressional Democrats should look at the latest Bloomberg/ Los Angeles Times national poll, which shows that by better than a 2-to-1 margin, American voters disapprovingly say the new Congress is engaged in ``business as usual'' rather than producing promised change.

The two biggest losers if the Senate fails to approve an immigration bill will be Bush and Democratic Senate leader Harry Reid.

The wisest Democratic voice has been Ted Kennedy, who has been involved with every major immigration bill for more than 40 years. It would be a huge mistake, he says, to postpone action figuring there would be political gains and a better chance under a Democratic president.

Emotions `Inflamed'

``If we do nothing, people will ask legitimately, `Why couldn't the Democrats deal with this overarching issue,''' Kennedy says in an interview. ``If we don't enact comprehensive changes now, the climate isn't going to get better; the emotions will just get more inflamed.''

The Massachusetts lawmaker says he thinks there will be a Democratic president in 2009 and ``we can come back to the parts of the bill that don't work. That will be a lot easier than trying to deal with it from scratch.''

A new Democratic president -- or, for that matter, a Republican -- would inherit a full plate of challenges: a health- care crisis; the need to deal with costly and popular entitlement programs such as Social Security; global warming; a North Korea with eight nuclear bombs; and an Iran on the verge of joining the nuclear club -- not to mention the Iraq war.

Like the current president, and the country, he or she will be better off if Congress takes one of these challenges off the plate and enacts immigration reform.

(Albert R. Hunt is the executive editor for Washington at Bloomberg News.)

To contact the writer of this column: Albert R. Hunt in Washington at ahunt1@bloomberg.net.

Last Updated: June 24, 2007 08:30 EDT