Women with college degrees are expected to be a major force in Tuesday's midterm elections, resulting in Democrats taking the majority in the U.S. House of Representatives, according to a leading election forecaster.

"This is really, in my opinion, the year of the fired-up female college graduate," said David Wasserman, editor of House races at the nonpartisan newsletter The Cook Political Report.

"Women with college degrees are the ones who vote" and they give President Donald Trump only a "27 percent approval rating in the most recent poll," he said.

In a CNBC interview Monday, Wasserman said Democrats should also benefit from what he called "the Red exodus," referring to 41 House GOP seats without an incumbent on the ballot.

"Democrats have a reasonable shot at picking up 15 of those seats. If they even get 12, then they'll be halfway to the 23 they need for the majority," he argued on "Power Lunch."

Democrats need a net gain of at least 23 House seats to wrest control from the GOP.

The current balance of power in the 435-member House is 235 Republicans, 193 Democrats, no independents and seven vacancies.

"Our current forecast is the Democratic gain of between 30 and 40 seats. We think anything from 20 to 50 is well within the realm of possibility," Wasserman said.

"We go from these surge elections for the party out of power," which in 2016 favored then-candidate Trump and Republicans, to "check-and-balance elections," like what's shaping up two years later, Wasserman said.

Among the other concerns for Republicans, he said, are independents "voting in large numbers for Democrats because they want to temper the impact of President Trump."

Democrats are also "outspending Republican incumbents in most of the tight races that will determine House control," he said. "They are raising staggering sums of money."

Wasserman related an anecdote from a discussion he said he had with a Republican incumbent in the House.

The congressman said, according to Wasserman, "Forty percent of the voters in my district absolutely hate the president and want to impeach him. Forty percent of voters in my district love Trump and will never leave him. And 20 percent are what I would describe as 'normal people.'"

Wasserman argued it appears that those 20 percent, extrapolated out nationally, "are breaking towards Democrats, at least in a lot of those outer suburban seats."

On the U.S. Senate side, Republicans, who hold a slim majority of 51-49 seats, are expected to retain control.