AUSTIN, Texas (AP) — As Texas flashes signs that November's election could wind up the closest in decades, Republican John Cornyn and Democrat MJ Hegar clashed over the response to the cornavirus pandemic and the confirmation of a Supreme Court justice Friday night in the only scheduled debate of their U.S. Senate race.

Cornyn, who has been in the Senate since 2002 and is seeking a fourth term, faces an unusual fight in fast-changing Texas, where shifting suburbs and a booming population have increased the chances of Democrats unseating him.

Hegar, an Air Force veteran who narrowly lost a U.S. House race in 2018, is an underdog in a state where Democrats haven't won statewide in 25 years. The debate in Austin offered her the biggest stage yet to go after Cornyn and earn a boost with early voting in Texas starting Tuesday.

Cornyn tried casting Hegar as too liberal from the outset in an attempt to tie her to Senate Minority Leader Chuck Schumer, while she attacked an 18-year record that she contends has failed to deliver results.

“Hi, I’m MJ Hegar, I’m a Purple Heart combat veteran and a working mom of two, and I am your opponent,” Hegar told Cornyn. “I am the person you’re running against, as inconvenient as that is for you."

As for the coronavirus, Cornyn said he would not support a national lockdown or a mask mandate, while Hegar said she backed a “national strategy" based on recommendations from health officials. Both tested negative for COVID-19 before the debate and stood a modest distance apart at podiums.

“We don't need the government to fill the void that we should fill ourselves by acting responsibly at the local level to keep each other safe,” Cornyn said.

Ahead of confirmation hearings set to begin Monday for President Donald Trump’s Supreme Court nominee, conservative Judge Amy Coney Barrett, Hegar did not commit to how she might vote over expanding the number of justices on the Supreme Court.

“Right now the only arguments I'm hearing are how it would benefit one party over another. We have enough legislators that make decision on how it impacts their party," Hegar said.

Alarms are flashing red throughout Republican Senate campaigns after Trump’s overbearing debate performance and COVID-19 diagnosis sent the party’s poll numbers cratering, particularly among the suburban white women and moms who helped elect him in 2016.

Republican prospects for holding its 53-47 majority in the Senate have been darkening for months. Democrats are zeroing in on Maine and Arizona, along with Colorado and North Carolina, as top targets. They are also making a run at widening their Senate map into reliably Republican states, including Iowa and South Carolina.

Texas also makes the list. Two years ago, former congressman Beto O'Rourke came within three points of ousting Republican Sen. Ted Cruz, a surprisingly close finish that overnight reset Democrats' perennially low expectations in America's biggest red state. Hegar, however, has not captured the same visibility in a campaign that has been limited by the pandemic and had to also contend with surviving a crowded Democratic primary.

She narrowly won a runoff this summer but went on to report raising more than $13 million since July, by far her strongest fundraising stretch. Cornyn has not reported his most recent figures but began the race with a significant cash edge.

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AP’s Advance Voting guide brings you the facts about voting early, by mail or absentee from each state: https://interactives.ap.org/advance-voting-2020/