The bottom is falling out from under Florida's once hugely popular governor.

A new Miami Herald/St. Petersburg Times/Bay News 9 poll finds only 42 percent of likely Florida voters think Charlie Crist is doing a good or excellent job as governor, by far the worst approval rating of Crist's 34 months in office.

As Crist seeks a promotion to the U.S. Senate, the race to succeed him is shaping up to be one of the closest the state has seen in decades. Democrat Alex Sink is statistically tied with Republican Bill McCollum, 38 to 37 percent.

That 51 percent of the Republicans in the poll rated Crist's performance as fair or poor is particularly ominous for someone facing an aggressive U.S. Senate primary challenge from former state House Speaker Marco Rubio of Miami.

``After nearly three uneventful years in the people's mansion in which unemployment has reached double digits across the state and the real-estate boom turned into a foreclosure nightmare, Charlie Crist has finally made something drop like a rock -- his approval ratings,'' said pollster Tom Eldon, echoing the governor's promise to make property taxes plunge.

Still, Crist's political troubles appear to be more about his own vulnerability than Rubio's strength.

In the Senate race, the poll found 50 percent of Republicans backing Crist, 28 percent Rubio, and 22 percent undecided. Even little known and 22 points behind, however, Rubio poses a real threat to the self-described ``people's governor'' no longer appreciated so much by people who overwhelmingly see Florida headed in the wrong direction.

ON THE FENCE

One in four voters were undecided between McCollum, the state's attorney general, and Sink, the state's chief financial officer. Half of the independent voters surveyed were on the fence.

``They're the whole ball of wax,'' pollster Kellyanne Conway said. ``As go the independents, there goes the race.''

The telephone survey of 600 registered voters was conducted Oct. 25-28, for The Miami Herald, St. Petersburg Times and Bay News 9. The poll was done by Schroth, Eldon and Associates, whose clients primarily are Democrats, and the Polling Co., which mainly works with Republicans. The margin of error was plus or minus 4 percentage points, overall and slightly more than 6 percentage points for questions asked solely to Democrats or Republicans.

Throughout his term, Crist has enjoyed remarkably strong poll numbers given the shape of Florida's economy. He is leader of a state where fewer than one in three voters see Florida headed in the right direction, and only 7 percent say their personal economic situation had improved in the past year.

``You have a state that's in deep pain and you have a governor that fails to acknowledge that the state is suffering,'' Eldon said. ``They don't see Crist fighting for the state. They see him running for the Senate.''

Crist has been battered with negative publicity in recent months, from questions about his heavy U.S. Senate fundraising schedule to criticism over his appointment of former campaign manager George LeMieux to fill Mel Martinez's unfinished Senate term. The governor's problems with the Republican base may have started in February when he stood on stage with President Barack Obama in Fort Myers in support of the $787 billion stimulus package.

Two-thirds of Republican voters said they disagreed with Crist's decision to appear with Obama and support the stimulus package and nearly half said they strongly opposed it. Overall, 48 percent of voters said they supported Crist's appearance and 42 percent opposed it.