PHOENIX (AP) — Down in the polls just days before Arizona voters begin casting ballots, Republican Sen. Martha McSally came out swinging against her Democratic challenger in their only face-to-face debate Tuesday, accusing retired astronaut Mark Kelly of obfuscating his true beliefs.

Kelly accused McSally and President Donald Trump of failing to lead the country through the coronavirus outbreak, bringing on an economic calamity and leaving people suffering. He presented himself, as he has throughout the campaign, as an independent voice uninterested in partisan politics.

Each returned over and over to their favored theme throughout the 90-minute debate that touched on the response to COVID-19, the Supreme Court, health care, immigration, guns, climate change and more. Both at times drew on their experience as combat pilots, Kelly for the Navy and McSally for the Air Force.

McSally unveiled a new nickname for her rival, branding him “counterfeit Kelly," a phrase she used at least 10 times as she made the case that the Democrat's independent rhetoric would give way to a liberal voting record in Washington. Her appeal is aimed at conservative-leaning voters who may be turned off by Trump and drawn to Kelly's message of independence.

“You have a choice here,” McSally said. “You have somebody who’s been a fighter for you and will continue to be a fighter for Arizona, or a counterfeit who will enable the radical left and their agenda to be forced on us.”

Kelly, a first-time candidate, faced perhaps his toughest challenge of the race after spending much of the year campaigning through virtual events from his home. He didn't hold his punches, saying McSally sat by while Trump squandered time to respond aggressively to the pandemic and help people through the economic fallout.

“Senator, you understand this as a pilot: you guys did step one of the emergency procedure, and then you didn’t do anything else,” Kelly said. "And that is a colossal failure."

Kelly has repeatedly declined to say whether he’d vote for Sen. Chuck Schumer, the Democratic leader, to be majority leader if his party takes control of the Senate. He's also declined to take a position on eliminating the filibuster, a requirement for most major legislation to get 60 votes in the Senate, which many Democrats see as a major impediment to their ability to enact their agenda. He offered no further clarity on either question Tuesday.

On the filibuster, he said only that he'll give it “careful consideration" if it comes up.

“Washington is broken, and this highlights how broken it is that we’re having these fights over old Senate rules,” Kelly said.

McSally said Kelly was “trying to say basically nothing to get elected.”

The faceoff provided McSally a much-needed chance to gain ground on Kelly, who has consistently led the race in polling and fundraising, just before voters begin casting ballots. In-person early voting begins Wednesday and election officials around the state will begin dropping absentee ballots in the mail the same day.

Throughout the campaign McSally has carefully avoided criticizing Trump, who maintains overwhelming support within her Republican base but is unpopular with many of the more moderate voters who will decide the election.

She deflected repeated questions about whether she’s proud to support Trump or would have been proud to serve under him during her Air Force career. But she did offer a rare criticism of the president for his repeated comments critical of the late Sen. John McCain, the beloved Arizona Republican who died in 2018. She was appointed to his seat, and the election will decide whether she or Kelly finishes McCain's last term.

“I publicly and privately, repeatedly talked to President Trump and asked him to stop attacking John McCain," McSally said. “Quite frankly, it pisses me of when he does it.”

Kelly, a former Navy pilot, is married to former U.S. Rep. Gabby Giffords, who survived being shot in the head during a constituent event in Tucson in 2011. The couple went on to found an advocacy group, now known simply as Giffords, that works around the country to advance gun-control laws such as a universal background check requirement.

McSally fought to pierce Kelly’s independent image and yoke him to the left wing of the Democratic Party. She pointed to endorsements by the Giffords gun group of liberal Democrats including U.S. Reps. Ilhan Omar and Rashida Tlaib, and former Arizona gubernatorial candidate David Garcia.

McSally also attacked Kelly for ties to China, noting he spoke fondly of several trips to the communist nation and co-founded a company that received an investment from a Chinese firm.

Kelly hammered on McSally's votes to repeal former President Barack Obama’s health care law, which he says would leave people with preexisting health conditions facing high costs, if they can get coverage at all.

As an Air Force pilot, McSally was the first American woman to fly in combat and later the first woman to command a fighter squadron in combat. After retiring, she was elected to the U.S. House from the district once represented by Giffords, repeatedly eking out narrow victories in a closely matched district. She ran for Arizona’s other Senate seat in 2018 but lost to Democrat Kyrsten Sinema, and Gov. Doug Ducey later appointed her to the seat held by McCain until his death of an aggressive brain cancer.

The candidates, their aides and the moderators were tested for COVID-19 before the debate, and they were separated on the set by plexiglass screens. McSally and Kelly did not shake hands.