U.S. Sen. Jon Tester of Montana will face Republican Tim Sheehy in Monday night's debate

BILLINGS, Mont. (AP) — Montana Republican U.S. Senate candidate Tim Sheehy admitted Monday that derogatory comments he made about Native Americans last year were “insensitive.” But Sheehy rejected his opponent's calls to apologize during a contentious debate in a race that turned out to be crucial for control of the Senate.

Incumbent U.S. Sen. Jon Tester challenged Sheehy last year over comments in which the Republican told a group of laughing supporters that he was “aligning with all the Indians while they're drunk” while at a ranch on Crow Indian Cattle worked reservation

“Yes, insensitive,” replied Sheehy, a former US Navy SEAL. “I come from the military, like many of our tribal members. You know, we make insensitive jokes and sometimes jokes that are unpleasant.”

Sheehy then tried to steer the discussion toward the immigration crisis, but Tester continued to press him.

“Tim, the statement you made demeans Native Americans in this country,” Tester said. “You’re a big guy, just apologize.”

“They apologize for opening the border,” Sheehy replied.

The bitter exchange during the final minutes of the debate highlighted the growing tensions between the two campaigns as the contest enters its final stages.

They are all vying for support from the state's small group of moderate Republican and independent voters who are seen as crucial to victory in November.

Sheehy sharply criticized Tester during the debate for his ties to lobbyists, who have donated more to the Democrat than to any other member of Congress this election cycle, according to the nonpartisan group OpenSecret.

“While I was fighting in Afghanistan. He ate lobbyist steak in DC,” Sheehy said.

Tester, in turn, accused Sheehy of wanting to ban abortion, even though the Democrat tied his own campaign to a voter initiative that would enshrine abortion as a right in the state constitution.

“I want to see Roe reinstated,” Tester said of the U.S. Supreme Court decision that overturned Roe v. Wade and allowed some states to severely restrict abortions. “My opponent, on the other hand, feels exactly the opposite. He feels more entitled to make this decision than the women.”

Tester is the last remaining Democrat holding high office in Montana, and the race is expected to be the most expensive in the state's history. Republican Party leaders, including former President Donald Trump handpicked Sheehy in hopes of toppling Tester, a 68-year-old farmer.

Republicans only need to gain two seats in November to win the Senate majority when a new Congress convenes next year. They are generally believed to have a castle West Virginiawhich means Montana could make the difference.

Trump won Montana by about 17 percentage points in 2020. Building on the former president's popularity in the state, Sheehy has often tried to lump Tester in with President Joe Biden and Vice President Kamala Harris. The Republican's goal is to highlight public discontent over the administration's efforts to curb illegal immigration at the southern border.

“Democrats on the Hill refused to hold the government accountable for the largest mass migration in the history of this country,” Sheehy said in response to a debate question.

To soften the attacks, Tester skipped the Democratic National Convention last month, declined to endorse Harris and avoided mentioning her on the campaign trail. He opposed the government's tightening pollution regulations for coal-fired power plants and urged it to do more to combat immigration.

“Look, I'll be the first to tell you that President Biden hasn't done a good job on the southern border,” Tester said Monday.