GLEN ELLYN, Ill. — Thousands of Republican volunteers were deployed this weekend in a "Super Saturday" push to protect their House majority — knocking on doors, handing out flyers, and calling voters.

The Congressional Leadership Fund (CLF), a super PAC backed by House Speaker Paul Ryan, has been aggressive on television airwaves, but Saturday showcased their national field operation, making around 400,000 contacts with voters.

Since 2017, the group’s tallied 15 million interactions, already reaching many on their data-driven list of conservative and swing voters multiple times.

"We’re having these ongoing conversations with voters. Giving them that extra reason to go out and vote, hopefully that juices turnout for Republicans in the midterms,” CLF Communications Director Courtney Alexander told NBC News.

The CLF, which pledged to spend $100 million this midterm cycle, spread its staff and volunteers across 34 competitive congressional districts. NBC News followed a field team in Glen Ellyn, west of Chicago, Saturday afternoon.

"We're targeting local issues in local communities, it's different in each congressional district," Alexander said when asked about the message to voters. "Here in Illinois we’re talking about the Great Lakes, whereas in Washington we’re talking about Salmon hatcheries, and in Florida we’re talking about the Everglades."

CLF's push is a sign of how seriously outside groups on both sides are taking the 2018 midterm battle. Volunteers in Illinois wore shirts with the words "Call. Knock. Win. Repeat!" on the back on Saturday.

Buoyed by an energized democratic base, Democrats believe they are well positioned to flip the 23 legislative seats they need in order to snatch back control of the House.

One of their top targets is Illinois sixth congressional district, home to Republican Rep. Peter Roskam. Roskam has been reelected by near 20-point margins in the past, but represents a suburban Chicago district that Hillary Clinton won by seven points.

It's a top target for national and state Democrats and CLF knows this, building a field office in a low-profile office building deep in the district.

The room mirrors a typical campaign office, filled with GOP-themed posters, flyers advocating for the congressman, and a whiteboard listing weekly contact goals.

Their aim: to keep Roskam’s Democratic challenger Sean Casten at a distance.

"GDP! Good grief, it's just amazing," Susan Dahlstedt said to a group of CLF volunteers that knocked on her door in Wheaton, Illinois, referring to gross domestic product and strong economic numbers overall.

The strong Trump supporter who suggested to the young group "he can keep his mouth shut sometimes" said she fears a democratic majority voting to impeach the president.

"We’ve got to keep the house, it’s really essential," Dahlstedt said soberly, promising to vote in November.

A few blocks over, Michael Vassola saw the same volunteers walk past his house. It’s a Republican effort he says he’s never seen before in his neighborhood.

"This is very much a staunchly Republican place," he said. "You didn’t even see Republican signs because it was assumed that everyone was voting Republican."

But Vassola added: “I’ve lived in this neighborhood for a while and I’m seeing more and more Sean Casten signs — including in the one in front of my house.”