(NewsNation) — Union endorsements are pivotal to the Democratic ticket, but they don’t guarantee members will support Vice President Kamala Harris and Minnesota Gov. Tim Walz when the time comes, a NewsNation panel said Monday.

United Auto Workers President Shawn Fain blasted former President Donald Trump on stage at the Democratic National Convention, calling the GOP nominee a “scab” both on a T-shirt and verbally.

Fain was just one of the labor leaders to speak on the first day of the convention. Working class support of Harris is nothing new. In the days following President Joe Biden’s exit from the race, she garnered endorsements from dozens of unions nationwide.

UAW worker and delegate Dallas Dean from Michigan told NewsNation he believes Fain is the “greatest” union president. He adds he’s all in on Harris.

“Labor has to have an even playing field and Trump says he’s going to throw everyone in jail if they go on strike,” Dean said.

Stirewalt, along with fellow NewsNation hosts Chris Cuomo and Elizabeth Vargas, discussed the Harris-Walz campaign’s ability to secure union support ahead of the 2024 presidential election Monday.

“Teachers unions, police, fire, government worker unions,” “The Hill Sunday” host Chris Stirewalt said. “That’s the mainstay of the Democratic Party.”

Cuomo acknowledged the importance of union support, pointing out that the specific union makes a big difference, depending on which part of the country you’re in.

That’s especially true since some unions are withholding endorsements for fear of being overlooked, according to Stirewalt.

“If you belong to one party, you are taken for granted, and it becomes impossible for you to get the things that you want from them, because your votes aren’t in doubt,” he said. “But the other side of that is that if you fool around, right, and you lose the connection to the party, if you are seen as being disloyal, seen as being separate, then your access goes down.”

Cuomo posited that, to get the most support, candidates should look at how union members are voting rather than the union itself.

Stirewalt agreed, adding: “Trump will win 70% of the Teamsters [Union]’s votes, regardless of who the Teamsters officially endorsed.”

NewsNation’s Stephanie Whiteside and Pat Hunt contributed to this report.