TRENTON, N.J. (AP) _ Gov. Christie Whitman's re-election drive has hit a speed bump: New Jersey's highest-in-the-nation auto insurance rates.

Whitman rolled back income taxes 30 percent in her first three years in office and became a rising star in the Republican Party. She had hoped to ride her theme of ``promises made, promises kept'' to an easy victory.

Instead, she finds herself in a surprisingly tough race.

Democratic challenger Jim McGreevey, little-known before winning the nomination, has risen in the polls while pounding away at the auto insurance issue. Recent polls show him to be anywhere from 12 points behind to neck-and-neck.

``This is a tough one to figure out when you consider the fact that so many other numbers for Whitman are good,'' said David Rebovich, political scientist at Rider University. ``There are good numbers on the unemployment rate, jobs and the economy. Crime is down, the environment is clean. And she's barely leading. She just hasn't been able to appease folks about auto insurance.''

While Whitman gained fame for her income tax cuts, a growing number of residents believe those cuts have been negated by a rise in property taxes. And McGreevey has been able to cash in on voter discontent over Whitman's failure to reduce auto insurance rates, which average $1,013 per car.

She put the issue atop her legislative agenda but was unable to persuade leaders of her own party to trade cuts of up to 25 percent for limits on lawsuits. She signed a watered-down law and promised to keep fighting.

McGreevey, 40, a hard-driving, suspender-wearing state senator and Woodbridge mayor, wants a 10 percent rate rollback to be paid for by fraud prevention efforts and also proposes public hearings on all rate increases.

``I represent families who consistently confront mortgage payments, auto insurance costs, college tuition _ the day-to-day financial challenges of middle-class life,'' said McGreevey, who repeatedly portrays the millionaire Whitman as out of touch with middle-class voters.

Whitman has responded with an ad campaign charging that McGreevey, as mayor, doesn't even pay car insurance. The city picks up the tab.

In her short time in office, the governor has been on vice presidential short lists, rebutted President Clinton's State of the Union address and served as co-host at the Republican National Convention.

But the 50-year-old Whitman _ the only governor up for re-election this year _ knows that even giants of Jersey politics can be vulnerable. After all, she is the one who nearly defeated ``unbeatable'' Sen. Bill Bradley seven years ago.

``I always thought this was going to be a close race,'' Whitman said. ``We have a lot of work to do. I don't take anything for granted.''

For his part, McGreevey concedes Whitman is still the favorite heading into the Nov. 4 election.

``My mother continues to say novenas. I'm confident she has lit every candle in every available church,'' said McGreevey, an Irish Catholic.

McGreevey is working hard to secure the old Democratic coalition of labor and urban voters, which broke down four years ago during Democratic Gov. Jim Florio's re-election bid. Since then, New Jersey has twice elected Democratic U.S. senators and given Clinton a landslide.

More than half of New Jersey's registered voters list no party affilation.

Voters responding to polls have given Whitman low marks on auto insurance and declared it the most important issue. Taxes, Whitman's strength, placed a distant second.

Another factor in the race is the possibility that a Libertarian candidate who promises to outdo Whitman in cutting government and taxes may join the televised debates.

Whitman has proven ability to charm television audiences. McGreevey looks younger than his age but can be shrill in speeches, and struggled in televised debates.

``Whitman's first advantage is the economy,'' said Rutgers University political scientist Steve Salmore, who consults for GOP candidates. ``Her second advantage is McGreevey. I simply don't believe he's credible enough for people.''

``Voters may not like everything Whitman has done, but that may not be enough for them to give up on her.''