Nelson, whose campaign can’t afford to advertise, is relying on outside liberal groups who have run $7.5 million in ads on his behalf. | AP Photo Scott edges Nelson by 3 in Senate race poll

Outspent by nearly 3-1, Sen. Bill Nelson (D-Fla.) is trailing Gov. Rick Scott by a marginal 3 percentage points in a new poll of what could be the most expensive U.S. Senate race in history.

Scott leads Nelson 47-44 percent in the Mason-Dixon Polling & Research survey, a net shift of about 4 points in the Republican’s favor since the firm’s last poll in February when the race was a dead heat. The margin of error for the poll of 625 registered Florida voters is plus or minus 4 percentage points. The poll was conducted July 24-25.


Mason-Dixon pollster Brad Coker said he wouldn’t be shocked if the race got tighter and that it remains too close to call on Election Day.

“It’s going to be a slugfest,” Coker said. “Nelson is hoping for a blue wave, and Scott is counting on Trump motivating his base of voters. Rick Scott has yet to have a landslide win. So I don’t anticipate him winning by a big amount if he does win."

Indeed, Scott won each of his last two statewide races by 1 percentage point in favorable Republican years. Nelson has won three terms in the Senate, but usually against weak opponents in favorable years for Democrats.

One of the biggest changes in the race since February: pro-Scott money. And lots of it.

Combined with the spending of four outside groups, Scott’s campaign has spent at least $21.5 million on TV ads in the race since spring. Nelson, whose campaign can’t afford to advertise, is relying on outside liberal groups who have run $7.5 million in ads on his behalf.

Scott is winning 84 percent of Republicans and 12 percent of Democrats compared to Nelson who’s winning 80 percent of Democrats and 7 percent of Republicans in the poll, meaning Scott is doing both better with his base than Nelson and is pulling more support from Nelson’s base than Nelson is from his. Scott is also winning independents by 47-43 percent.

Another potentially troubling sign for Nelson: the poll samples slightly more Democrats than Republicans, but Republicans tend to turn out in higher percentages than Democrats during midterm elections. So the poll could be ever so slightly underestimating Scott’s relative advantage.

Also, the poll shows, President Donald Trump isn’t as toxic to the Florida electorate as Democrats hope. About 46 percent have an unfavorable view of him and 43 percent have a favorable view. That roughly matches Trump’s ratings before the 2016 elections.

“Even before Trump won Florida, he was underwater,” Coker said. “I don’t think he has ever been above 50 in a Florida poll. But he managed to win the state."