Republican U.S. Rep. Marsha Blackburn has extended her lead over Democrat Phil Bredesen to 9 percentage points in Tennessee's U.S. Senate race, according to a new Fox News poll, the latest survey showing the conservative congressman pulling ahead.

The Fox News poll, released Wednesday, found that Blackburn, R-Williamson County, is the preferred choice of 50 percent of likely voters in Tennessee compared with 41 percent for Bredesen, former Tennessee governor.

Five percent said they are undecided, while the remaining people polled either said they didn't know whom they will vote for or wouldn't vote.

It marks marks the fourth public poll in the last 24 hours showing Blackburn with a lead greater than 5 percentage points as the race has increasingly nationalized over the past month.

Early voting ends Thursday ahead of next Tuesday's election.

The phone survey, a sample of 718 likely voters conducted via cellphone and landlines, was taken between Oct. 27 and Oct. 30 and has a margin of error of 3.5 percentage points.

More:2 new polls show Blackburn leading Tennessee's US Senate race a week from Election Day

An NBC/Marist poll released Tuesday had Blackburn up 5 percentage points, which was within that poll's margin of error. Vox Populi Polling found her up 6 points. And a poll from Cygnal, a Republican-aligned Alabama-based firm, also gave Blackburn a 6-point lead.

Trump's approval rating now at 58% in Tennessee, poll finds

Like the other polls, the Fox News poll found soaring approval ratings for President Donald Trump, with 58 percent of likely voters now approving of his job compared with 39 percent who disapprove. Blackburn has campaigned aggressively as an ally of Trump's agenda.

The poll found Blackburn with the lead despite a greater share of Democrats, 92 percent of those polled, saying they back Bredesen than the percentage of Republicans, 87 percent, who are loyal to Blackburn.

But working in Blackburn's advantage, according to a Fox News analysis of the poll, is that more likely voters identified as Republicans by a greater than 20-point margin.

More:New poll from Alabama-based Cygnal shows Blackburn with 6-point lead over Bredesen

A poll taken in early October by Fox News had Blackburn up 5 percentage points, 48 percent to 43 percent.

Fox News conducted the poll under the joint direction of Anderson Robbins Research, a Democratic polling firm, and Shaw & Company Research, a Republican-aligned group.

In Tennessee's race for governor, the poll found Republican Bill Lee leading Democrat Karl Dean among likely voters by a margin of 54 percent to 37 percent. The findings are consistent with other polls.

Reach Joey Garrison at jgarrison@tennessean.com or 615-259-8236 and on Twitter @joeygarrison.