Even though the effort fell short, the strong showing by Newman — who pushed Lipinski to the brink in the first competitive primary of his career — will give those groups a jolt of momentum as they look to push Democrats to embrace progressive positions.

The congressman would be a virtual lock to hang onto his seat in November, since his Chicago-area district is a Democratic stronghold. And Republicans have disavowed their only candidate, Arthur Jones, a white supremacist and Holocaust denier.

The New York Times is reporting that the Illinois Republican Party could fund an independent challenger, but it's unclear who that would be and third-party challenges have a poor history of success.

Lipinski’s victory will give the longtime congressman a sigh of relief despite the close margin.

The co-chairman of the centrist Blue Dog Coalition was targeted by a slew of progressive groups who characterized his views as out of step with the Democratic Party. He’s come under fire for voting against marriage equality, ObamaCare and the DREAM Act in 2010.

Abortion politics were a main focus of the primary battle. He’s also taken heat for being one of only six House Democrats who voted in 2013 for a ban on abortions after 20 weeks.

Newman was propelled by a coalition of progressive and more mainstream groups, which spent more than $1.6 million to help get her elected. That push helped Newman close the significant gap in the polls, since she started out with low name recognition and lackluster fundraising.

Lipinski had the advantage of incumbency as well as more cash on hand, even with Newman out-raising him toward the end of the primary. He argued that constituents are well aware of his record and that his views are in line with his district.

He’s represented the suburban Chicago district since 2005, when he succeeded his father who had held the seat for more than a decade, a favorite of the Chicago political machine that has long flexed its muscles there. He also has strong relations with many in organized labor for his positions on strengthening manufacturing and opposing unfair trade deals.

But the primary challenge did soften Lipinski’s positions — at least on immigration. Despite his past opposition to the DREAM Act, Lipinski said last year that he’d support a Deferred Action for Childhood Arrivals (DACA) bill if it came up in the House.

As the race continued to tighten in the final stretch of the race, more lawmakers and groups threw their support behind him in a last-ditch effort.

And he even got some last-minute help from Susan B. Anthony List — a major anti-abortion group that typically backs Republicans for office — which spent six figures on canvassing efforts, digital advertising and mailers.

The internal debate over supporting candidates who don’t back abortion rights roiled the party last year and divided progressives and party leaders, who defended the Democratic Party as a big-tent party.

Lipinski’s win shows that there’s still a path forward for Democrats who mirror him ideologically, though Newman's strong showing leaves it an open question as to how long that door might remain open.