Helping 15-year-old Jimmy Kenney out with a school paper can win a politician a lifetime of personal affection.

But don’t expect that to include a presidential endorsement.

That’s the lesson learned Wednesday morning by former Vice President Joe Biden, who woke up like everyone else to the news that now-Philadelphia Mayor Jim Kenney had just endorsed U.S. Sen. Elizabeth Warren of Massachusetts for president.

A lot can change in 45 years.

Kenney was a sophomore at St. Joseph’s Prep, with a paper deadline fast approaching. It was 1974. Gerald Ford was in the White House, having just pardoned predecessor Richard Nixon, who had resigned when it became clear he would be impeached.

A lot can also stay the same in 45 years.

Biden was in his first term as a U.S. senator from Delaware. Kenney called his office in Washington to ask for an interview for his paper. He was instructed to take the train from Philadelphia to Washington, where he met Biden on the platform at Union Station. They boarded the next northbound train, with Kenney conducting his interview on board.

Kenney, who told Clout this story in 2008 as Biden was on the Democratic ticket for vice president, said he recalled getting “an A or a B-plus” on the paper.

The larger lesson? Always make time for students.

“It just always inspired me that a person at that level would make time for me,” Kenney told Clout in 2008.

Fast-forward to 2019, when Kenney skipped Biden’s first official campaign event in Philadelphia, an April fund-raiser at the home of Comcast senior executive vice president David L. Cohen. He has expressed both affection for Biden and concern about the campaign.

“I really like him," Kenney told The Inquirer in July. “I do think he’s had some missteps lately. I think he can be out of touch a little bit.”

Kenney’s endorsement of Warren in a news release and a video — he called her “a tough and determined leader” who has “what it takes to defeat Donald Trump” — makes no mention of Biden.

A spokesperson for Kenney’s reelection campaign later said “the mayor has the utmost respect and affection for the vice president, but he set his personal feelings aside and endorsed the Democratic candidate who shares his progressive vision, and who he believes is best able to defeat Donald Trump in 2020 and lead our nation in the post-Trump era.”