Three years ago, State Sen. Sharif Street stood proudly behind Cherelle L. Parker at an election night victory party after voters picked her to be Philadelphia’s first female mayor.

At the time, Street was the head of the state Democratic Party, and he had enthusiastically supported her in a crowded primary.

It appears that now-Mayor Parker is returning the favor.

Parker is scheduled to announce Wednesday that she is endorsing Street, who is now running for Congress in an ultra-competitive Democratic primary. Street is seeking to replace outgoing U.S. Rep. Dwight Evans and represent Pennsylvania’s 3rd Congressional District, which encompasses a large swath of Philadelphia and is one of the bluest districts in the nation.

» READ MORE: Philly’s three-way fight to replace Dwight Evans in the U.S. House enters a volatile final stretch

It was perhaps predictable that the mayor would ultimately endorse Street, as he is building a coalition similar to her own. They are both allied with the powerful Philadelphia Building Trades and Construction Council, and the leaders of the Democratic City Committee who endorsed Street also largely backed Parker three years ago.

Still, the mayor’s backing is a critical vote of confidence for Street, who is endorsed by the city’s Democratic Party, but is up against two other formidable candidates.

Physician Ala Stanford, a first-time candidate, is being boosted by a deep-pocketed super PAC spending more than $2 million in her favor, making her the only candidate with television ads on the air. And State Rep. Chris Rabb has the support of the city’s progressive movement.

» READ MORE: Meet the 4 Democrats vying to replace Dwight Evans in Congress

In an interview Tuesday before the announcement, Street would not confirm the endorsement, but he described Parker as “a great friend.”

“Her endorsement will carry a lot of weight,” he said. “She’s an incredibly effective and important leader.”

The mayor was joined at the news conference Wednesday by several other elected officials there to endorse Street, including influential West Philadelphia lawmakers: State Sen. Vincent Hughes, City Councilmember Curtis Jones Jr., and State Rep. Morgan Cephas, who dropped out of the congressional race last month.

Street has now won powerful allies across the district. His own geographic base is in North Philadelphia, where his father, former Mayor John F. Street, built a political power center in the 1980s.

Last week, a contingent of Southwest and South Philadelphia lawmakers — including State Sen. Anthony Williams and Council President Kenyatta Johnson — also announced their support for Street.

Parker is the city’s most visible Democrat from the voter-rich neighborhoods in Northwest Philadelphia. In addition to being the city’s mayor, she is the ward leader in the high-turnout 50th Ward.

Democratic ward leaders and committeepeople boost their chosen candidates by knocking on doors to get their neighbors to vote and handing out “sample ballots” of party-endorsed candidates to voters as they enter polling places.

Those strategies are often determinative in elections where voters know little about the candidates, such as local judicial races. In more high-profile contests such as mayoral or congressional races, ward support helps candidates, but is not seen as an insurmountable advantage.

Some of the progressive groups backing Rabb have developed their own get-out-the-vote machinery, and a successful media-driven campaign like Stanford’s can make up for disadvantages in ground-level organizing.

» READ MORE: Philly’s competitive U.S. House race narrows — but big questions loom

Parker’s endorsement of Street means the powerful Northwest Coalition, an influential political organization that has produced some of the city’s most prominent Black leaders, will be split in this election.

Evans, who has held the 3rd District seat for the last decade, endorsed Stanford to succeed him. Evans and Parker have been close for decades — he walked her down the aisle at her 2010 wedding — making Parker’s choice to campaign for Street all the more significant.

The mayor’s backing is also a critical step for Street as he tries to unite Black voters behind him. Black and Latino voters lifted Parker to office when she ran for mayor in 2023, and recent polling in the 3rd Congressional District shows they remain some of her staunchest supporters.

This is a breaking news story and will be updated.

Staff writer Sam Janesch contributed to this article.