Joe Biden is the front-runner for the Democratic nomination for president next year. But a Philadelphia labor leader says he should remember where he came from and meet with workers.

Pat Eiding, president of the AFL-CIO in Philadelphia, invited 20 Democratic contenders to town for a mid-September forum where “rank and file” union members can listen to their pitches and ask questions.

Biden, who plays up his ties to Scranton, has not committed to attending.

That prompted Eiding to lash out in an NPR interview released Friday, warning that the former vice president is taking union support for granted.

“He always calls himself a Pennsylvanian at heart. His headquarters are here in Philadelphia. But his folks haven’t found the importance of coming together and talking to our workers. And so, that’s very disappointing,” Eiding told NPR. “There’s got to be some respect for the working people if they want their vote.”

Eiding told The Inquirer on Friday that he spoke with Biden’s campaign Thursday and insisted his organization is not “feuding” with the candidate. The forum will be held Sept. 17 at the Convention Center, with a second day added on Sept. 18 if needed.

“If Joe Biden comes, wonderful,” Eiding told The Inquirer. “If he doesn’t, we’re still going to have the event. Certainly it would be wonderful if he was there. I mean, he lives down the street.”

So far, Eiding said, the AFL-CIO has confirmed seven candidates to attend: Vermont Sen. Bernie Sanders, Minnesota Sen. Amy Klobuchar, billionaire activist Tom Steyer, entrepreneur Andrew Yang, former U.S. Rep. Joe Sestak of Delaware County, U.S. Rep. Tom Ryan, and author Marianne Williamson.

Former U.S. Rep. Bob Brady, chairman of the Democratic City Committee, said he spoke twice to Biden on Friday trying to secure his appearance at the forum. Biden is trying to work it into his schedule, Brady said, and offered to appear for the AFL-CIO on another day.

Eiding turned that down, Brady said, concerned a lone appearance might look like an endorsement.

“He’s going to try to figure out a way to get there,” said Brady, a longtime friend of Biden’s.

In the NPR interview, Eiding also took issue again with Biden’s decision on the day he launched his campaign to attend a fundraiser at the West Mount Airy home of David L. Cohen, senior executive vice president of Comcast Corp.

“First place he goes is [the home of] the head of Comcast. No connection with labor," Eiding said. "And they go forward. And it was a little disturbing, because I thought, ‘Well, here we go again’” — a reference to Eiding’s belief that Hillary Clinton took organized labor for granted in 2016.

Biden has long touted his ties to organized labor, and is staking his candidacy on a bet that he can connect to working-class voters in Pennsylvania and key Midwestern states that abandoned the Democratic Party for Donald Trump in 2016.

The day after Biden launched his campaign in April, he held his first rally with hundreds of workers at a Teamsters hall in Pittsburgh, where he proposed raising the federal minimum wage to $15 an hour, up from $7.25, and rolling back Trump’s tax cuts, which he said primarily benefited the wealthy.

Biden’s campaign noted that he has attended a number of labor events across the country and met privately with union leaders in Iowa and New Hampshire, the two states that cast the first ballots in the primary. Biden has been endorsed by the International Association of Fire Fighters.

“Joe Biden has fought for working people his entire life, and as he said at his official campaign launch in Philadelphia, as president he would strive every day to build ‘an economy that rewards work, not just wealth,’” a spokesperson for the Biden campaign said in a statement.

The statement added: “Vice President Biden is as proud to call Patrick Eiding a friend as his campaign is to call Philadelphia home.”

This is not the first time Eiding, a labor leader with a voice Democrats listen to in Pennsylvania, has been critical of the party or of Biden, whom he counts as a friend.

Eiding in May called a meeting to tell local labor leaders to “keep their powder dry” in presidential politics. Biden was riding high then, having just held a packed rally on the Benjamin Franklin Parkway.

“This whole Joe Biden thing kind of disturbs me a little bit,” Eiding said at the time. “I think jumping out too soon will leave us in a position that’s too fragile.”

And the AFL-CIO helped organize a “Workers Stand for America” rally on the Parkway in August 2012, in part driven by anger that the Democratic Party was holding its presidential convention in North Carolina, a state seen as hostile to labor unions.

“I think the message has to be to all politicians,” Eiding said in 2012. “We as working people in this world need to be recognized for the things that we need.”