In the lead-up to former Gov. Phil Bredesen’s decision to launch a bid for the U.S. Senate, polling commissioned by the Democratic Senatorial Campaign Committee found the former Nashville mayor had slightly more support than U.S. Rep. Marsha Blackburn.

The poll found Bredesen was leading Blackburn by 46 percent to 41 percent among likely voters, with 13 percent undecided.

The survey was performed Oct. 20-22, more than a month before the Nashville Democrat entered the race.

Among independents alone, Bredesen’s lead increased in a head-to-head matchup with Blackburn. Forty-eight percent of independents favored Bredesen, while 31 percent were with Blackburn.

► More:Blackburn would beat Bredesen in head-to-head matchup, according to poll from Trump-aligned PAC

When respondents were asked if they were highly committed to their candidate, 83 percent of self-identified Bredesen voters said they were very or somewhat committed to the Democrat, versus Blackburn, who netted 89 percent.

“Thus, the ‘lines’ seem to be drawn fairly early, with perhaps fewer persuadable voters than average,” states a Garin-Hart-Yang memo analyzing the poll.

The poll tried to reflect Tennessee’s political makeup, with Republicans consisting of 42 percent of all respondents, 29 percent Democrats and 25 percent independents.

The poll did not survey respondents about any other Republican in the race beyond Blackburn. Also seeking the GOP nomination are former U.S. Rep. Stephen Fincher, former Memphis Grizzlies doctor Rolando Toyos and perennial candidate Larry Crim.

► More:Former Gov. Phil Bredesen launches US Senate bid with campaign video

► More:Exclusive: Former Republican Rep. Stephen Fincher enters Tennessee U.S. Senate race

► More:US Rep Marsha Blackburn launches Senate bid

► More:Former Memphis Dr. Rolando Toyos enters race for Corker's Senate seat

The poll found 48 percent of respondents had a favorable image of President Donald Trump, while 42 percent had a negative view.

In addition, the survey asked respondents whether they would support a U.S. senator who is independent of Trump and would serve as a check on him or someone who will work with the New York real estate mogul.

Half of all respondents said they supported a U.S. senator who is independent of Trump, and 42 percent said they’d want someone who sides with the president. Among independent voters, the split is 51 percent in favor of a candidate who is a check on Trump versus 39 percent.

The poll also found 39 percent of respondents had positive feelings about Bredesen, while Blackburn netted just 31 percent. In terms of negative views on each, Bredesen and Blackburn had 13 percent and 29 percent, respectively.

Roughly three out of four respondents said they were familiar with both candidates.

The poll, which was conducted by Garin-Hart-Yang, surveyed 601 likely Tennessee voters. It had a margin of error of plus or minus 4.1 percentage points.

A spokeswoman for the Democratic Senatorial Campaign Committee declined to say how much money they plan on pumping into the U.S. Senate race.

Reach Joel Ebert at jebert@tennessean.com or 615-772-1681 and on Twitter @joelebert29.