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.

``When you appear on stage with a Democrat, you're taking sides against your party. I think it hurt the party, like a betrayal,'' said 62-year-old Margarita Duarte of Hollywood.

Asked about Crist appointing LeMieux to the U.S. Senate seat, only one-third of voters said they approved of the decision, while 26 percent disapproved and 40 percent did not know.

Obama also earns weak job approval marks from Florida voters, with 46 percent saying he is doing a good or excellent job and 51 percent calling it fair or poor. The voters who delivered Florida's 27 electoral votes -- independents -- have turned on him, with nearly 6 in 10 negatively assessing Obama's performance.

Crist may be lucky that voters tend to have stronger feelings, good and bad, about the president than they do for him. For instance, only 6 percent of voters said Crist is doing an excellent job -- compared to 21 percent for Obama -- and 16 percent said Crist is doing a poor job, compared to 30 percent for Obama.

``Seventy-five percent think Crist has done a fair or good job,'' Conway noted. ``It's a gentleman's C, but maybe that's enough.''

PLAYING CATCH-UP

Indeed, the pollsters agreed that the little-known Rubio has a long way to go to catch Crist. If the governor were in dire trouble, even an unknown challenger would likely be closer than Rubio is.

``The most positive number for Crist in the entire survey is that he's at 50 percent among Republican primary voters -- despite all that has happened,'' Conway said.

Nearly half the Republicans who opposed Crist supporting Obama on the stimulus package still said they would vote for him.

Other polls in recent weeks have variously found 59 percent of Florida voters approved of Crist's job performance, and 48 percent approved.

In the Herald/Times/Bay News 9 poll, Crist beat Rubio among every demographic group including Hispanics, where 40 percent backed Crist, 30 percent the Cuban-American Rubio and 30 percent were undecided. The Miami Republican was strongest in central Florida, where he trailed by 10 percentage points, and weakest in Crist's home territory of Tampa Bay, where he trailed by 29 points.

The Republican showdown has overshadowed the Democratic primary, which still looks largely unformed. U.S. Rep. Kendrick Meek of Miami leads former Miami Mayor Maurice Ferre 26 to 6 percentage points. More than two-thirds of voters are undecided, reflecting how little known the two Democrats are across the state.

Florida's gubernatorial contest is shaping up to be one of the closest the state has seen in decades. In contrast to other recent surveys that show Republican McCollum with an edge over Democrat Sink in the governor's race, the Herald/Times/Bay News 9 poll found a dead heat.

Both siphoned the same amount of support from one another's parties, and they were evenly divided among independents. Sink had an edge among women and in her home turf of Tampa Bay, while McCollum led slightly among men and in his home base in central Florida.

``You have two candidates stuck around the 40 percent threshold,'' Eldon said. ``It's two very evenly matched candidates at the gate and it's going to be a battle to the finish in America's most purple state.''

Herald/Times writers Shannon Colavecchio and Marc Caputo contributed to this report. Beth Reinhard can be reached at breinhard@MiamiHerald.com.