Cao, a 25-year Navy veteran whose past political experience was limited to a promising but failed bid in 2022 for a blue-leaning northern Virginia U.S. House seat, faced an uphill battle in the race, according to political observers. The Commonwealth hasn't elected a Republican to the upper chamber since 2002 with the late John Warner, a centrist with an independent streak.

Kaine won his last race in 2018 by 16 percentage points. When he announced his reelection bid last year, he said he was preparing for a tough race and wasn't taking anything for granted. He noted that "Virginians will vote for Republicans in statewide elections," as they did in 2021 for Gov. Glenn Youngkin.

Political scientists had said there was a narrow path to victory for the GOP given Virginia's moderate electorate, aversion to former President Donald Trump in the 2020 election and Kaine's salience with voters.

"This is definitely an uphill climb for the Republican Party in this state, particularly with a candidate who could be more easily tied to Trump," Rebecca Bromley-Trujillo, a Christopher Newport University political science professor, told The Associated Press in June.

Cao scored Trump's endorsement during a crowded Republican primary race. And the former president stated then that Cao would help stop inflation, secure the border and "defend our always under siege Second Amendment."

In their only debate in October, Cao and Kaine sparred over everything from illegal immigration to tariffs on foreign goods, with each candidate sticking mostly to the tenets of their respective political parties.

Cao criticized COVID vaccine mandates for service members and the chaotic troop withdrawal from Afghanistan when asked about the military's collective failure to recently meet recruiting goals. He also condemned diversity, equity and inclusion efforts at the debate in Norfolk, which is home to the nation's largest Navy base.

"When you're using a drag queen to recruit for the Navy, that's not the people we want," Cao said. "What we need is alpha males and alpha females who are going to rip out their own guts, eat them and ask for seconds. Those are the young men and women that are going to win wars."

Kaine, who is on the Senate Armed Services Committee, responded by saying that railing at DEI "is a red herring," and the real challenge is informing more Americans about the benefits of the military when only about 1% of the population serves in the armed forces.

"We need to do a better job of talking about the GI Bill and other benefits as well as the tremendous leadership training that you get in the military," Kaine said.

Cao made a decent showing in 2022 in his race against Democratic U.S. Rep. Jennifer Wexton in blue-leaning northern Virginia. He lost by 6.5 percentage points in a district that Biden won two years earlier by 19 percentage points.

Kaine has won all of his statewide races, including as governor and technically as a vice presidential candidate in 2016, when he and Hillary Clinton carried the Commonwealth but lost the general election to Trump and Mike Pence.