As mayoral race heats up, do endorsements really matter?

This week, the rappers Diddy, Jay-Z, and Nas got together to talk politics and lend support to Democratic Mayoral hopeful Ray McGuire.

"We have the power to ignite this and light this up," Diddy said in the video call, released by McGuire's campaign.

"You've got my endorsement, you'e got my love and support," Nas said to McGuire, a former Citigroup executive.

The rappers are some of the many celebrities to step into the Mayoral contest.

Andrew Yang has Amy Schumer in his corner, Maya Wiley has won the support of Gabrielle Union and Kathy Griffin. And Scarlett Johannson has endorsed Scott Stringer. But do any of these endorsements matter?

"Endorsements may be a way to cut through the clutter and get people to focus," said veteran political strategist Hank Sheinkopf.

He says particularly in a crowded field like the Democratic primary endorsements can help.

But not all endorsements are equal, and the ones that are most valuable come not from big celebrity names, but big unions.

Get breaking news alerts in the FOX5NY News app. Download for FREE!

"Labor union endorsements matter because the members of unions vote, also they bring troops into the street  to bring out the vote for the person that union has endorsed," SHeinkopf said.

Eric Adams got the backing of the Uniformed Fire Officers Association this week, one of many union nods he's picked up. Kathryn Garcia has the endorsement of a number of labor unions.

Columbia University Professor of Political Science Ester Fuchs says, particularly in a ranked choice race like we're about to have, even the backing of small political clubs can help move the needle.

"Even if you have 25 members and they support someone, they could help contribute to a margin of victory in a ranked choice race that is likely to be very tight," Fuchs said.

As for celebrity backings, she says while there's not much research on how they factor into election results,  in a fragmented field a little star power could rub off.

"Scarlett Johansen endorsed Scott Stringer and a lot of people like her and might think Scarlett Johansen is cool, I'm gonna take another look at Scott Stringer and then they may like him for other reasons too."

The primary is June 22.