Leaders of the country’s major labor unions are currently withholding their much-coveted endorsements from Democratic presidential candidate Hillary Clinton, reported The Hill. The reluctance stems from the frustration that Clinton has yet to side with labor unions over trade legislation.

Clinton has yet to take a hard stance in favor of workers in regards to the Trans-Pacific Partnership (TPP), which is why AFL-CIO President Richard Trumka has also been courting Sen. Bernie Sanders and potential candidate Joe Biden. Officials say that Trumka is trying to coax pro-labor support out of Clinton against the TPP.  

“Say you’re in love with a girl and want to marry her,” said Democratic strategist Brad Bannon. “She’s playing it cool. So you figure the best way to make her jealous is to flirt with someone else. Trumka wants to marry Hillary, but until she’s willing to make stronger commitments to labor, he’s going to flirt with Bernie and Biden.”

In the heat of their race, Sanders and Clinton have been vying for endorsements from the AFL-CIO, International Brotherhood of Teamsters, and the Service Employees International Union (SEIU). Neither group has officially endorsed a candidate.