LEBANON, Tenn. — Republican U.S. Rep. Marsha Blackburn and Democratic former Gov. Phil Bredesen are set to face off in their first debate in a critical race for U.S. Senate in Tennessee.

The two rivals will debate Tuesday evening at Cumberland University in Lebanon. Hosts include The Tennessean, the League of Women Voters of Tennessee, WTVF-TV and WNPT-TV. The event will be broadcast live.

The race to replace retiring Republican Sen. Bob Corker could be pivotal for the slim 51-49 Republican Senate majority.

In a poll conduct in mid-September, Bredensen held a five point edge over Blackburn, 50 percent to 45 percent among likely voters in the Tennessee Senate race. Roughly one in six voters said there’s a chance they’ll change their mind before Election Day.

Health care tops the list of voters’ most important issues, with 29% calling it tops in their Senate vote in Tennessee. The economy follows in Tennessee at 22%, immigration lands third at 16%. Voters who say health care is their top issue are broadly supportive of the Democrat in both contests, breaking for Bredesen over Blackburn by 71% to 21%. Both economy and immigration voters favor the Republican in each state. Blackburn holds a whopping 50-point lead among immigration voters in Tennessee and a 10-point advantage among economy voters.

The CNN Polls in Tennessee were conducted by SSRS September 11 through 15 among random statewide samples reached on landlines or cellphones by a live interviewer.

In Tennessee, results for the full sample of 1,000 respondents have a margin of sampling error of plus or minus 3.6 percentage points. It is 3.9 for the sample of 852 registered voters and 4.3 for results among the 723 likely voters.

A second debate has also been confirmed for Oct. 10 at the University of Tennessee’s Howard H. Baker Jr. Center for Public Policy in Knoxville.