Karl Rove: How to tell if a 'red wave' is forming early on election night

Fox News contributor Karl Rove broke out his whiteboard Thursday to reveal what early midterm election night trends he'll be watching that could signal a "slam dunk" for Republican candidates.

Rove joined "America's Newsroom" with the night's roadmap, starting with the first polls to close in Kentucky and Indiana.

"I'm going to be looking at those congressional districts to compare the results from 2020 to 2022 results to find out how much of a swing there is against the Democrats," Rove explained, "which we're likely to see in these races, because this swing is going to be very important throughout the entire night."

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"If there's a two or three-point swing against the Democrat performance… there will be a certain number of losses. If it's a four or five, six, seven, or eight-point swing, there will be a lot more."

Rove then moved to the next polls to close in Georgia and Virginia, with consequential races for governor, the Senate and the House.

If Georgia Republican Gov. Brian Kemp wins reelection against Democrat Stacey Abrams by a "serious margin," Senate hopeful Herschel Walker can be expected to perform better, Rove noted.

In Virginia, three "highly competitive" races are the ones to watch for House control. Virginia’s 2nd district and 7th district, home to incumbent Democrats, are shifting right to "Lean R" and "Toss-Up," according to the latest Fox News Power Rankings.

"If the Republicans win one, it's going to be a good night. If they win two it's going to be a great night. If they win all three, watch out. It is going to be a slam dunk for Republicans," Rove said.

Rove is using election results from 2020, a presidential election year, versus the 2018 midterms, as a "judgment" of the current administration and Democrats who hold the power. 

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"I'm looking at 2020 because that's some sort of baseline for this election," Rove said. "That's when the Democrats won the House races that they won. That's where we got a sort of sense of what the Democrat ceiling might be given the presidential vote. And so I'm going to be comparing to there to see how much risk the Democrats are in compared to the 2020 number that they received."

As Election Day nears and the nation prepares to head to the polls, it's still unclear which party has the best chance to win control of the Senate. But four volatile races in different regions of the country will likely determine the balance of power between Democrats and Republicans.

In Georgia, Republican Herschel Walker leads incumbent Democratic Sen. Raphael Warnock by 1.6%, according to the Real Clear Politics (RCP) average of polls taken in recent weeks, well within the margin of error.

Republican Blake Masters in Arizona has made similar strides. While he still trails incumbent Democratic Sen. Mark Kelly by 2.3%, according to RCP, that lead is much narrower than the nearly 10-point lead Kelly held in September.

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In Nevada, Republican Adam Laxalt, the state's former attorney general, leads incumbent Democratic Sen. Catherine Cortez Masto by 1.9%, according to RCP, with much of his boost in support appearing to come from independent voters in the traditional battleground state.

In arguably the most high-profile race this year, Democratic Pennsylvania Lt. Gov. John Fetterman holds a slight 0.6% lead over Republican Dr. Mehmet Oz, according to RCP, one of the closest margins in the race since the primary elections.

Fox News' Brandon Gillespie contributed to this report.