Teamsters President Sean O'Brien revealed on Tuesday that Sen. Bernie Sanders, I-Vt., stopped communicating with him after O'Brien spoke at the 2024 Republican National Convention, saying the senator's attitude and level of access have changed.Speaking with The Free Press' Bari Weiss, the union boss said Sanders "doesn't talk to me anymore."O'Brien spoke at the 2024 Republican National Convention but said he never heard back from the Democratic National Committee after requesting to speak. The Teamsters did not endorse Trump or Harris in 2024.Asked if he used to talk to Sanders often, O'Brien said he used to do rallies with him: "I think he looks at it as a betrayal of not endorsing the Democratic Party."DEMOCRATS LASH OUT AT MISINFORMED AS TEAMSTERS UNION MAKES LANDMARK NON-ENDORSEMENT"He's never said that, but his whole attitude and access have completely changed towards us," he said.O'Brien said his staff called Sanders and his team last week because they were working on the Faster Labor Standards Contract Act, which O'Brien said was a trimmed-down version of the PRO Act."He's got a problem with it and his staff [were] not too nice to my staff. So it's like, we're only as good to people when we're carrying that water, but I guess that doesn't matter," he said."I mean, look, I like the guy. I have respect for him. I saw him on Joe Rogan. I don't know. I mean, this is the problem with politics. People take things too personal. And when you don't go along to get along because you're actually listening to people you represent, and they don't talk to you anymore, you know, that's the problem. It's fine," O'Brien continued.TEAMSTERS BOSS PRAISES TRUMP FOREIGN FILM TARIFF, CONDEMNS HOLLYWOOD'S 'UN-AMERICAN ADDICTION TO OUTSOURCING'Sanders' team did not immediately return a request for comment.The Teamsters president also criticized former Vice President Kamala Harris during the interview, accusing her of pressuring the union for an endorsement.He described one off-putting encounter Teamsters leader Joan Corey allegedly had with the 2024 presidential candidate in a photo-op line."So, Joan goes in the line and Joan says, 'I'm Joan Corey. I'm a vice president with the Teamsters Union,' and [Harris] pointed her finger at Joan and said, 'Teamsters better get on board,' and so Joan says, 'Excuse me?' 'Yeah, Teamsters better get on board. I don't know why you haven't endorsed me yet.' So she comes back, and she tells me this, and I'm like, 'The nerve!'"CLICK HERE FOR MORE COVERAGE OF MEDIA AND CULTUREOBrien went on to claim that when Harris met with the unions executive board, which had prepared a slate of 16 questions, she only answered four."She really didnt answer the questions, and then on the fourth question, my chief of staff slides me an index card and says, This is the last question. Shes not answering anymore, because she wanted to pontificate and give her speech of why the country is the way it is, why we should endorse her," he said.Harris didnt respond to a request for comment.Fox News' Alexander Hall contributed to this report.