The Georgia senate showdown between incumbent Senator Raphael Warnock, a Democrat, and his Republican challenger, Herschel Walker, is now the most expensive race of the 2022 midterm election, according to OpenSecrets, a nonprofit that tracks political spending.

“As of right now we’ve seen more than $425 million going to total spending,” said Anna Massoglia, the editorial and investigations manager at OpenSecrets. She said much of that money comes from super PACs. They can raise and spend unlimited amounts of money.

Massoglia added that super PACs have to disclose their donors. But sometimes, those super PACs also get contributions from so-called “dark money” groups. And they can keep the source of their money a secret.

“We’re seeing a lot of gray money spending where some of the donors are disclosed or there are layers of opacity,” she said.

Massoglia said right now, Warnock is winning the money race, raising more than twice as much cash as Walker. Charles Bullock is a political science professor at the University of Georgia. He said incumbent senators like Warnock have a built-in advantage.

“Because they’ve established relationships with potential contributors during the course of their work in the Senate, and then contributors know that incumbents usually win,” he said.

Both candidates in the runoff are spending lots of money on getting out the vote. Andra Gillespie, a political scientist at Emory University, said that’s expensive, even if the people knocking on doors are volunteers.

“You have to give them the materials, you have to outfit them with t-shirts, you have to pay to feed them,” she said.

Gillespie is seeing the stepped-up get-out-the-vote efforts firsthand. She lives and votes in Atlanta. She got a handful of text messages reminding her to vote before the general election. Now, she said both sides are bombarding her.