Osama bin Laden is the famous terrorist; Spence Abraham a little-known Republican senator from Michigan. Their only link is Arab ethnicity, but that's been enough to make Mr. Abraham the target of a nasty political fear campaign.

"Why is Senator Spencer Abraham trying to make it easier for terrorists like Osama bin Laden to export their war of terror to any city street in America?" asks a newspaper ad with photos of the two men side by side. At least Mr. Abraham isn't depicted wearing a turban.

This and more is the handiwork of FAIR, the least accurate acronym in politics. It stands for the Federation for American Immigration Reform, a group of population-control zealots whose goal is no immigration at all. FAIR is pouring hundreds of thousands of dollars into deceptive TV, radio and newspaper ads aimed at damaging Mr. Abraham before his re-election bid this year.

At stake is more than one senator's future. Mr. Abraham has drawn FAIR's fury because he dared to rescue Republicans from their mid-1990s detour as an anti-immigrant party.

"Their goal is to beat me so they can intimidate others who favor legal immigration," says the 47-year-old grandson of Lebanese immigrants. His fate will influence whether Republicans follow the (minority) path of the crabby, nativist European right.

Also at issue is whether a Republican can get political credit for resisting his own party's reactionaries. Liberals are constantly lecturing conservatives to police their own. But when one of them comes under political fire for doing so, liberals suddenly turn mute.

Just ask former Gov. David Beasley, who tried to remove the confederate battle flag from South Carolina's capitol during his first term. His reward was revolt on the right but silence or worse on the left. Columnist James Pinkerton has reported that South Carolina Democratic Party chairman Dick Harpootlian helped finance a "Southern Heritage" group that attacked Mr. Beasley from the pro-flag right.

As for Mr. Abraham, no politician did more to break the GOP's anti-immigrant fever of the mid-1990s. After Proposition 187 passed in California, he fought efforts in Congress to reduce legal immigration. He foresaw that barring education to six-year-old aliens wasn't the best way to attract swing Hispanic voters.

Other Republicans finally got that message after their election rout in 1996, and George W. Bush now tells anti-immigrant questioners that "family values don't stop at the Rio Grande River" -- not that liberals give him any credit.

FAIR won't forgive Mr. Abraham for replacing its advisory board member, the restrictionist Alan Simpson, as chairman of the Senate immigration subcommittee. Worse still, the Michigan freshman has built a coalition to expand temporary visas in order to ease America's growing high-tech labor shortage.

This drives FAIR to distortion. Michigan's jobless rate may be 2.7%, meaning that jobs go begging. But FAIR's ads claim that the senator "is again pushing a bill to import hundreds of thousands more foreign workers to take American jobs. Our jobs."

The opposite is closer to the truth. U.S. companies are so desperate for labor they're paying bounties for successful referrals. Without the ability to import skilled workers, U.S. companies will move those and other jobs overseas. Julie Holdren, CEO of the Olympus Group, told Congress that for every foreigner she employs, "I am able to hire 10 more American workers."

But jobs aren't the real issue with FAIR. Their problems are people and economic progress. "I can't even get to work in this town," says FAIR's Washington-based executive director, Dan Stein . "How many lanes do you want on [Interstate] 270?" He adds that his "optimal, long-range" U.S. population would be fewer than 150 million; good luck getting there from today's 270 million.

Mr. Stein claims FAIR intended no ethnic slur by linking Mr. Abraham to an Arab terrorist. "We thought Abraham was Jewish," he says. But this denial is hard to believe, given FAIR's history. Its former chairman, John Tanton, once told a Knight-Ridder reporter he was concerned that too many immigrants are Catholic.

Mr. Stein is less forthcoming about FAIR's ads, especially their financing. "I'm not going to say who's paying for the ads," he says, which is certainly convenient if the funders are unions and trial lawyers.

Also strangely silent is Mr. Abraham's Democratic opponent, Rep. Debbie Stabenow. Though she courts high-tech corporate cash and claims to be a New Democrat, she's had nothing to say about FAIR's anti-Abraham barrage. Her staff didn't even return phone calls on the subject.

Come autumn Ms. Stabenow will inevitably attack Mr. Abraham as one more right-wing "extremist." But who's the greater political risk: a senator willing to fight his own party's nativist wing, or a challenger so desperate to win she won't denounce a campaign of fear? FAIR may yet end up helping Mr. Abraham.