MISSOULA, Mont. ― Battling for his political survival, Sen. Jon Tester (D-Mont.) spent much of Monday’s Senate debate against Republican rival Tim Sheehy on offense, accusing the wealthy rancher of helping fuel the state’s housing crisis, posing a threat to reproductive rights and lying to voters about his plans for federal lands.

From the opening seconds of their face-off at the University of Montana, Tester treated his opponent like the real threat he poses to his campaign for a fourth term, as well as Democrats’ tough odds of retaining control of the Senate next year.

Criticizing Sheehy’s record on protecting federal lands, a huge issue in Montana, Tester warned, “Watch out what people say in back rooms, folks.”

“What they say in back rooms, when they don’t think the recorder is going or the camera is running, is usually what they think,” Tester said. “And Tim said we need to turn our lands over to either his rich buddies or county government. That’s not protecting public lands.”

Tester knocked Sheehy repeatedly on land use, saying his opponent has “made an incredible transformation on this issue.” Tester cited HuffPost’s reporting, which first revealed that Sheehy had called for federal lands to be “turned over” to states or counties; failed to disclose his post on the board of the Property and Environment Research Center, a Bozeman-based property rights and environmental research nonprofit with a history of advocating for privatizing federal lands; and appeared to doctor a recent TV ad to remove PERC’s logo from the shirt he was wearing.

In defending himself, Sheehy falsely claimed that “no one, including myself, in that organization has ever advocated for selling our public lands ― never have, never will.”

In fact, in a 1999 policy paper titled “How and Why to Privatize Federal Lands,” PERC’s then-director, Terry Anderson, and others laid out what they called “a blueprint for auctioning off all public lands over 20 to 40 years.” (PERC previously told HuffPost that that 1999 paper “is not representative of PERC’s current thinking.”)

When asked about making housing more available to Montanans, Tester highlighted his legislation that would provide tax credits to new homeowners and then quickly pivoted to slamming “hedge fund folks buying homes and kicking people out” of the state, a veiled reference to Sheehy moving to Montana from Minnesota a decade ago. The senator has railed about the ultra-wealthy driving up costs in the state and spending millions to try to oust him from office.

But it was on the topic of abortion rights that Tester took his most direct aim at his GOP challenger, calling him out for opposing the state ballot initiative that would protect reproductive rights and criticizing his statements calling abortion “terrible” and “murder.”

“Women should be able to make their own health care decisions,” Tester said. “It shouldn’t be the federal government, a bureaucrat or a judge. Women should. That’s what Montanans like.”

Sheehy said he supported exceptions for abortion, such as in cases of rape, incest or when the life of the mother is at risk, but he criticized Democrats for not supporting abortion restrictions.

“At some point when there’s another viable life included, that life also has the right to protection. … Commonsense life legislation is what I support,” Sheehy said when asked if there should be a national standard on abortion.

Tester also attacked Sheehy over his comments last year calling for privatization of the U.S. health care system, warning that it would threaten Medicare, veterans care and the Indian Health Service.

Sheehy responded by calling health care “a moral obligation” but said that the private sector would be “able to do it better, faster and cheaper.” He decried a single-payer health care system, adding that “we can’t hand our health care to the government, that’s a disaster.”

The candidates’ discussion of the U.S.-Mexico border and the issue of immigration grew particularly heated. Sheehy accused Tester of helping create a migration crisis on the border, while Tester criticized Sheehy and other Republicans for blowing up a bipartisan Senate bill that would have toughened border enforcement because “party bosses,” including former President Donald Trump, came out against it.

“It could have been passed, but Tim Sheehy was against it before it was even released to read,” Tester said.

Tester backed Sheehy into a corner on his disparaging comments about Native Americans in Montana. A recording unearthed last month showed Sheehy peddling a racist trope about members of the Crow Tribe, in southeast Montana, and alcoholism.

“It’s on tape, once again, and you didn’t think anybody was listening,” Tester said. “But believe people when they say stuff in a back room.”

Sheehy acknowledged that the comments were “insensitive” and “off-color,” and said he takes accountability for that, but he stopped short of apologizing and accused Tester of trying to distract from the issues that affect Native communities.

“You’re a big guy; just apologize,” Tester said.

“Will you apologize for opening the border?” Sheehy fired back.

Tester is facing a barrage of multimillion-dollar GOP ads attacking him over his ties to national Democrats, including President Joe Biden and Vice President Kamala Harris, the Democratic presidential nominee. He has sought to distance himself from the Democratic Party as he trails Sheehy in polls of the hotly contested race. Trump beat Biden in Montana by 16 percentage points in the 2020 presidential election, a margin Republicans are hoping will flip Tester’s seat to their column and gain them control of the upper chamber along with it.

This has put Tester in a difficult position of trying to remind voters that he and Biden aren’t always on the same page despite his record of supporting Biden’s major legislation in Congress.

“Biden has not done a good job on the southern border,” Tester said at one point, before adding, “But Congress needs to do its job, too.”