CHICAGO (CBS) — Two first-time Democratic candidates eked out victories in suburban congressional races on Tuesday, in districts that normally vote Republican, helping Democrats take control of the House.

Scientist and businessman Sean Casten defeated Republican U.S. Rep. Peter Roskam in the 6th District, which Republicans have held since 1973.

In an even bigger upset, Democrat Lauren Underwood, defeated four-term Republican U.S. Rep. Randy Hultgren in the 14th District. Underwood, a progressive African American, took 52 percent of the vote in a district which is 86 percent white and widely seen as a Republican stronghold.

Roskam, a six-term incumbent, said he’ll leave it up to the pundits to explain why he lost to a political novice in a district his party has held for more than four decades.

Political analyst Stephen Maynard Caliendo said Governor-elect J.B. Pritzker helped propel both Casten and Underwood to victory in the midterms.

“The amount of money that Pritzker was able to spend to get Democrats to the polls certainly helped,” he said.

More than 156,000 voters picked Casten over Roskam to represent parts of Cook, DuPage, Kane, and Lake counties.

With endorsements from well-known politicians, like U.S. Sen. Dick Durbin, Casten’s campaign lasered in on distaste for President Donald Trump, running ads telling voters Roskam voted with the president 94 percent of the time.

“I think that was probably smart. He’s not a very popular president at this point in time,” Caliendo said.

An emphasis on female voters helped initiate Underwood’s victory dance on Tuesday.

The 32-year-old nurse will join 90 women elected to the House, the most women ever to serve in the House at once.

Underwood’s win over Hultgren also makes her the first woman and first minority to represent the largely rural 14th District.

“To have a black woman representing that area is really historic; and it also speaks, I think, to changing demographics in the Chicago suburbs,” Caliendo said.

Underwood defeated Hultgren by less than 4 percentage points. Two years ago, Hultgren defeated his Democratic challenger by 18 points.