FREMONT, Neb. — Senate Majority Leader John Thune, R-S.D., is predicting Republicans will outperform the polls and retain their narrow Senate majority, even as GOP-aligned groups pull millions of dollars from struggling candidates and redirect resources to races that have suddenly become more competitive.

Thune has been crisscrossing the country campaigning for vulnerable Republicans ahead of the Nov. 3 election. He’s confident that they can hold onto their slim, 53-to-47-seat majority in the Senate but acknowledges that the GOP as a whole faces headwinds.

And as Election Day inches closer and closer, several contests across the country have tightened, like in Kansas, while others may be slipping away from Republicans, like in North Carolina or Georgia.

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Thune, in an interview with Fox News Digital on the trail supporting Sen. Pete Ricketts, R-Neb., was still optimistic about the GOP’s chances.

"I think there are a lot of races right now just looking at the polling that are up for grabs," Thune said. "I mean you could call them jump balls, however you want to say it. They're margin of error races, and there are some that are maybe a little out of the margin. But I do think the polling right now, like it has been in past elections, under-reflects the Republican vote."

"And I think you'll see some of that. So we're not giving up on any of them," he continued.

Republicans are hoping to defend six toss-up races this cycle, according to Cook Political Report. And several that earlier appeared as safe bets, like Mississippi and South Carolina, have recently shifted more favorably towards Democrats.

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The flow of campaign cash has been staggering during this midterm cycle, with Republican political action committees (PACs) and outside groups dumping hundreds of millions of dollars in key races across the country.

But where the money is being shifted could be more telling.

Earlier this month, the Senate Leadership Fund, a PAC closely aligned with Thune, moved money from Georgia to Kansas, where Sen. Roger Marshall, R-Kan., is locked in one of the more unexpected toss-up contests of the cycle.

The Senate Leadership Fund had initially pledged $44 million to bolster Rep. Mike Collins, R-Ga., in his quest to topple Sen. Jon Ossoff, D-Ga. But the incumbent first-term senator has been raking in campaign donations and consistently led Collins in polling.

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And in North Carolina, where former Republican National Committee (RNC) co-chair Michael Whatley is running to keep retiring Sen. Thom Tillis’ seat red against former North Carolina Gov. Roy Cooper, outside funding has begun to dissipate.

The Senate Leadership Fund similarly pulled back nearly all of its spending in the state earlier this month, a sign that confidence in Whatley’s ability to best Cooper was waning. Even President Donald Trump, who held a rally for Whatley on Tuesday, is worried about the race.

"I think he’s a great man, and I am worried about him," Trump told reporters earlier this month. "I hope he wins. He was a great leader for the whole Republican Party when I won, and he’d be a great senator."

Meanwhile, Thune was still bullish that Republicans could hold on, but ultimately, it would come down to getting the "low propensity, particularly Trump, voters out, and then you've got to work on winning the middle of the electorate."

"Turnout's going to be a big part of whether or not we're successful or not. And in every state I've been in, that is a clear-eyed focus of our candidates," Thune said.

"That's where resources are being invested. And I think that could be the difference for us come Election Day on whether or not we win a lot of these close races or not," he continued. "And I think that we're gonna outperform the polls for sure come Election Day."