The poll shows Rubio leading the field with 45 percent, followed by Gov. Charlie Crist at 28 percent and Meek at 21 percent. Only 6 percent of voters were undecided in the Mason-Dixon Polling & Research Inc. poll.
"There is simply no mathematical formula by which Crist or Meek can approach Rubio's 45 percent support level," said Mason-Dixon managing director Brad Coker.
Even if Meek were to bow out now, Coker said, the math isn't there. Early votes have already been cast and Meek's name would remain on the ballot.
"It was a pipe dream to begin with and if they were doing it, it should have been done a month ago," Coker said. "In three days how do you convince every Democrat who was going to vote for Meek that Crist is the guy?"
A combative Crist dismissed Coker's poll, arguing that Mason-Dixon had wrongly predicted down races in the past.
Coker warned that the biggest loser in the "ham-handed move'' could be Democratic gubernatorial candidate Alex Sink, who needs a robust turnout among Democrats, including African-Americans.
"The slight of Meek may cause some black voters to sit on their hands next Tuesday," Coker said.
Sink, campaigning in Miami, said she was focused on her campaign, but acknowledged, ''clearly it's a distraction."
Sink, who met with a number of African-American pastors Thursday night, did say she didn't believe black turnout would be depressed.
"They understand what's at stake," she said. "They're all supporting Meek very enthusiastically."
She wouldn't say whether she was involved in the back and forth in the Senate race.
Crist's admission that he's talked to leading Democrats about pushing their party's nominee aside — combined with Meek's denials — has created a "he said-she said'' sideshow that likely will only damage both of them, Coker said.
"Given that both already trailed Rubio … the timing of this debacle only deflects attention from any tangible arguments they could further make to convince voters not to back Rubio," Coker said.
The internal results of the poll show no major changes in the race, Coker said. Rubio retains a large lead among Republicans while Meek and Crist are splitting the Democratic vote. Rubio and Crist are splitting the independents.
The poll of 625 registered voters — all of whom said they were likely to vote in the November election — was conducted Oct. 25-Oct. 27.
The poll carries a margin for error of 4 percentage points.
The poll shows Crist's independent bid hurting him among voters: Since quitting the Republican Party to run as an independent, his unfavorable name recognition has jumped from 31 percent to a new high at 42 percent.
Meek's numbers remain mixed, Coker said, "but the perception that national party leaders were willing to throw him under the bus to stop Rubio is a move that has likely paralyzed his campaign."