Sen. Bernie Sanders (I-Vt.) has endorsed Marie Newman, the nonprofit executive challenging Rep. Daniel Lipinski (D-Ill.) in the March 20 Democratic primary — a week after House Minority Leader Nancy Pelosi (D-Calif.) said that she supported Lipinski for reelection.

“Marie Newman has made it clear that she will be a champion for working families in Illinois, which is why I am proud to support her campaign” said Sanders in a statement released by Newman’s campaign. “In Congress, Marie will fight for Medicare for All, a $15 an hour minimum wage, and providing workers with benefits such as paid sick leave, while protecting Medicare and Social Security. She will defend women’s rights, LGBT rights and ensure immigrants have a safe path to citizenship.”

Sanders has not previously endorsed a challenger to a Democratic incumbent, though he carried Lipinski’s 3rd District during his campaign in Illinois’s 2016 presidential primary. Lipinski, citing that result, said that he would support Sanders if he the senator won enough delegates to contest the nomination at the national convention.

“I will be the unabashedly progressive champion that women and families across this district and beyond deserve, never compromising on the values they work hard every single day to achieve,” said Newman in a statement.

In late February, Sanders traveled through Illinois, Iowa and Wisconsin to endorse several political allies now running for the House; while in Illinois, he had a conversation with Newman, who has given Lipinski the biggest challenge of his 14-year career in his suburban Chicago district.

By that time, Newman’s campaign had already won the backing of several influential left-wing and abortion rights groups, from NARAL Pro-Choice America to MoveOn to National Nurses United. Lipinski, who opposes abortion, warned that a “tea party of the left” was forming, suggesting that it would make it harder for anything to get done in Washington, and harder for Democrats to win the House.

But the unique circumstances of the race for the 3rd District have lowered the risk of Democrats losing the seat. Republicans did not field a serious candidate of their own, leaving their nomination to Art Jones, a local neo-Nazi activist and gadfly candidate. Candidates may file for write-in campaigns as late as September, but the district is reliably Democratic, giving 56 percent of the vote to President Barack Obama in 2012 and 55 percent to Democratic presidential nominee Hillary Clinton in 2016. Several other Democrats sometimes vote with Lipinski for new abortion restrictions and against left-wing health-care bills, but none in a district that voted solidly for Clinton.

Pelosi’s endorsement of Lipinski, offered quickly in response to a question at a news conference, was one of the only boosts he got from national Democrats. The Democratic Congressional Campaign Committee, which recently intervened unsuccessfully against a candidate in a Texas race, has not committed any resources to Lipinski.

“I’ve never gone to leadership for support, now or in the past,” Lipinski told The Washington Post in a short interview last month.

Asked for a response to the Sanders endorsement, a spokesman for Lipinski’s campaign sent a link to an article published today by the Chicago Tribune, about Newman and her husband partnering with a felon to invest in three local restaurants. Newman told the Tribune that she had not known about their partner’s legal past when they invested.