A new poll in Florida's very competitive U.S. Senate race shows Republican Gov. Rick Scott with a 3-point lead over Democratic Sen. Bill Nelson, 47 to 44 percent, with 9 percent undecided.

Considering the poll's 4-point margin of error, the race is essentially tied.

"There has been a small but clear shift toward Scott," Mason-Dixon Polling & Strategy says. Its previous poll in February showed Nelson with a 1-point advantage, 45 to 44 percent.

Nelson's numbers have been static since February of 2017 when he polled at 46 percent to Scott's 41 percent. Now, Nelson is at 44 percent and Scott is at 47 percent, with enough undecideds to swing this race either way.

Scott does better among white voters and men, and runs strongest in north and southwest Florida — traditional Republican strongholds. Nelson does better among women, blacks and Hispanics and in southeast Florida, the home of about one-third of all Democratic voters in the state.

Mason-Dixon says the I-4 corridor in central Florida is slowly trending in Scott's favor.

Scott is viewed more favorably than Nelson in the poll, 44 percent to 36 percent. President Donald Trump is viewed favorably by 43 percent and unfavorably by 46 percent.

Nelson is a runaway favorite among young voters, aged 18 to 34. He leads with that group 56 percent to 33 percent. But Scott leads or is tied among voters in all other older age groups.

Democrats likely cannot take back the Senate unless Nelson wins a fourth term in November.

Nelson is viewed as among the most vulnerable red-state Democrats in the country this cycle. He is also the only incumbent Democrat being outspent by his Republican rival, a point Nelson himself makes regularly in his fund-raising pitches to supporters.

In a pitch over the weekend, Nelson said: "Rick Scott has already spent more money against me than in my entire campaign spent in all of 2012, and with 101 days to go, he's just getting started."

Mason-Dixon surveyed 625 voters who said they were likely to vote this fall. The survey was conducted July 24-25 and has a 4 percent margin of error. Quotas were assigned to reflect past county voter turnouts.