HELENA, Mont. (AP) — Incumbent Republican U.S. Sen. Steve Daines is set to face his Democratic opponent, Gov. Steve Bullock, in the last debate of Montana’s U.S. Senate race — a key seat that Democrats hope to win in their bid to gain control of the Senate.

The debate is set to air Saturday evening on the Montana Television Network, a day after many counties in the state began mailing ballots to voters. The candidates will face questions on topics that have dominated the race, including the coronavirus pandemic.

Bullock was praised for his swift response in the spring, which included a shutdown order that helped keep the virus at bay. But as the state reopened in early summer, the case tally began to climb. A record number of new cases, hospitalizations and deaths were reported in recent days, as the governor delegated responsibility for precautions to local authorities.

Bullock, 54, is barred by term limits from seeking a third term in the governor’s mansion. He entered the Senate race in March, following a presidential bid that failed to gain traction.

President Donald Trump won Montana by 20 points in 2016, but Bullock’s entry into the race has put the Senate seat in play for Democrats, who must win at least three other seats in November to gain control of the Senate.

Daines, 58, has Trump’s endorsement and has praised the president for his handling of the pandemic. The former businessman was first elected to the U.S. Senate in 2014, following two years as Montana’s lone representative in the U.S. House.

The debate will be recorded remotely through an online platform as precautions are taken against the spread of the virus.