If the midterm elections were held today, Tennessee voters would pick their state's leading Democratic candidate for U.S. Senate over his likely Republican opponent, even though most voters in the state approve of President Donald Trump, a new poll finds.

Democratic former Gov. Phil Bredesen is likely to face Republican U.S. Rep. Marsha Blackburn in the race for Tennessee's open Senate seat in the 2018 elections.

The seat is opening up because incumbent Republican Sen. Bob Corker will not seek re-election. Corker had reportedly reconsidered his retirement, but eventually settled on not running.

The last Democrat to represent Tennessee in the Senate was Jim Sasser, who lost a bid for re-election in 1994 after serving three terms.

In the poll, conducted by the Democratic-leaning firm Public Policy Polling, 46 percent of voters said they would vote for Bredesen, while 41 percent favored Blackburn. The poll had a margin of error of plus or minus 3.1 percentage points.

Thirteen percent of the roughly 1,000 surveyed voters remained undecided. Of the voter pool, 33 percent identified as Democrats, 43 percent identified as Republicans and 23 percent identified as independent or other.

All in all, the latest polls and forecasts suggest a rapidly tightening race for the Senate candidates in Tennessee, a deeply red state that Trump won by nearly 30 percentage points in 2016.

Other polls have painted a muddled picture of Tennessee voters' views of the race. Oregon-based Triton Polling & Research found Blackburn with a 9-percentage-point lead over Bredesen, while Florida-based Gravis Marketing gave Bredesen a 2-point edge.

The Cook Political Report, a nonpartisan election analytics firm, labeled the Tennessee race a "toss-up."

Bredesen, a two-term governor who won all of Tennessee's 95 counties when he ran for re-election in 2006, is running on fixing the health-care system, the opioid epidemic and the economy.