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CHICAGO — Rep. Dan Lipinski of Illinois, one of the most conservative Democrats in Congress, narrowly won a primary Tuesday over a progressive newcomer who argued the congressman's views no longer reflect the Chicago-area district he has represented for seven terms.

Marie Newman, who was little-known when she decided to challenge Lipinski for the seat he inherited from his father, had backing from progressive groups as well as Sen. Bernie Sanders, who won Illinois' 3rd Congressional District by 9 points over Hillary Clinton in the 2016 Democratic primary.

Congressman Daniel Lipinski walks with wife Judy Lipinski after voting in the congressional primary election in Western Springs, Illinois on Monday. Kamil Krzaczynski / Reuters

With 97 percent of precincts reporting votes, Lipinski's margin over Newman was less than 2 percentage points. She told supporters in an email earlier Tuesday night that "there's a good chance we wake up in recount mode."

But recounts are unusual in Illinois, and the process is a difficult one.

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Although the Blue Dog caucus of moderate and conservative Democrats of which Lipinski is a part already has dwindled in recent years, his close nomination fight could embolden liberals in other races across the country.

She campaigned as the "true Democrat," blasting Lipinski for opposing abortion and voting against same-sex marriage and President Barack Obama's signature health care overhaul.

Lipinski was first elected in 2004, taking over a seat his father held for more than two decades. He faced little serious competition since then in the heavily Democratic district, which includes parts of Chicago's southwest side and several suburbs.

Lipinski described himself as a "workhorse" who delivered for the district, bringing in federal transportation dollars and jobs. That helped earn him the support of many labor organizations, including the Illinois AFL-CIO.

Marie Newman Kamil Krzaczynski / Reuters

He has called Newman and her supporters a "tea party of the left" and says their efforts to drive out Democrats with differing views will hurt the party and add to gridlock in Washington. Democrats, he said, should be united in fighting President Donald Trump, not going after each other.

"It's been blasting from both sides," said Joe Nowak, a 36-year-old trucking company employee who lives and voted in Summit. He said he didn't care about issues about guns or abortion but that he was supporting Lipinski because "he's been around the neighborhood."

But Suzanne Riordon, a 56-year-old investment banker from suburban Brookfield, said Lipinski has been a disappointment. She was particularly angry about his vote against the Affordable Care Act.

"I don't think Lipinski has our best interest at heart as a democrat and for what we want, what we the people have been asking for. He doesn't listen to us," she said. "He's been my congressman for a long time and I don't think he stands for what we stand for."

Newman is a small-business owner who also runs an anti-bullying organization. She says she will push for health care for all, a $15 minimum wage and a path to citizenship for immigrants brought to the U.S. illegally.

The GOP nominee is Arthur Jones, a self-proclaimed Nazi and Holocaust denier who was the only Republican to file for the office after the Illinois Republican Party unsuccessfully tried to recruit a candidate.