It was a moment that seemed to reflect the current political temperature, measuring just how momentous the midterm elections have become — and how the rhetoric has been amped up to match.

Any old criticism won’t do. In the closely watched Senate race in Arizona, “treason” was the accusation leveled Monday by Republican Rep. Martha McSally against her Democratic opponent, Rep. Kyrsten Sinema.

In the sole debate of the campaign, McSally, a retired Air Force colonel and combat pilot, asked Sinema to apologize for a 15-year-old radio interview about American intervention in Iraq and Afghanistan, suggesting that her comments were tantamount to levying war against the United States. Sinema responded by accusing the Republican of playing dirty.

The two women are squaring off for the seat being vacated by Sen. Jeff Flake (R-Ariz.) in a race that will help decide which party controls the chamber. Polling shows that the contest remains close ahead of the Nov. 6 vote.

The two-term Republican congresswoman lobbed the “treason” charge near the end of the hour-long debate, which featured fierce disagreement over other issues, including immigration and health care. Instead of answering a question about climate change, McSally turned to address her opponent directly about a CNN report last week that brought to light comments made in 2003 by Sinema, then an activist with ties to the Green Party.

As part of her effort to publicize a February 2003 antiwar protest in Patriots Square Park in Phoenix, Sinema appeared on the radio show of a local libertarian activist. The host, Ernest Hancock, laid out a rambling hypothetical situation — difficult to follow at times — and concluded by asking Sinema if she would be okay with him joining the Taliban.

“Fine, I don’t care if you want to do that, go ahead,” Sinema replied, before adding: “What we’re talking about here are two different things. When you say, ‘We owe something to the world,’ my definition of owing something to the world does not involve war and destruction.”

She then added that she wanted to get back to discussing her antiwar position.

McSally characterized Sinema’s response as saying that “it was okay for Americans to join the Taliban to fight against us.”

“You said you had no problem with that,” she said. “Kyrsten, I want to ask right now whether you’re going to apologize to the veterans and me for saying it’s okay to commit treason?”

As Sinema began to reply, the Republican added, “It’s treason.”

The three-term Democratic congresswoman dismissed the inquiry without revising her 15-year-old remarks.

“Martha has chosen to run a campaign like the one you’re seeing right now, where she’s engaging in ridiculous attacks and smearing my campaign,” Sinema said. “And she’s just trying to cut, cut, cut and not share the full picture. But the truth is that I’ve always fought for Arizona, and I’ve been proud to serve our state in elected office for over 13 years.”

As the hosts told the candidates that time had elapsed, McSally repeated again, “It’s treason.”

Her campaign later circulated a definition of treason under U.S. code, which speaks of waging war against the United States or aiding its enemies. The penalty envisioned is death or imprisonment paired with a steep fine. Anyone found guilty is also barred from holding public office.

Meanwhile, Sinema’s camp declared victory in the debate and retweeted a post from Grant Woods, a former Arizona attorney general, saying the Democrat was “calm, cool, and collected and her opponent wasn’t.” Sinema told reporters after the debate that the charge was “ridiculous,” and, when asked if she had encouraged people to join the Taliban, said, “of course not.”

The accusation by McSally marked an escalation of earlier efforts to counterpose her military service to the Democrat’s antiwar activism. Sinema rose from a hardscrabble childhood to finish Brigham Young University in just two years, later earning four graduate degrees — in social work, law, business and justice studies. She served as spokeswoman for the Arizona Green Party in 2000 and as a state legislator before winning a congressional seat in 2012.

McSally tacked hard to the right to fend off rivals in the Republican primary courting the endorsement of President Trump. She toughened her stance on immigration and held Flake, one of the president’s primary GOP adversaries, at arm’s length. She has even emulated the president’s coarse speech, saying in an ad, “I’m a fighter pilot and I talk like one.”

“That’s why I told Washington Republicans to grow a pair of ovaries and get the job done,” she added.

Her strategy appears to have paid off with the president. Trump is expected to stump for McSally on Friday in Mesa, east of Phoenix, the same day that former president George W. Bush is scheduled to hold a fundraising breakfast for the Republican candidate in Scottsdale, according to the Arizona Republic.

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