The United Auto Workers, the most visible union holdout in backing President Joe Biden‘s reelection bid, is expected to discuss its 2024 presidential endorsement during a conference that starts this weekend.

The UAW and a handful of other major national unions have so far refrained from endorsing Biden’s campaign, despite the administration’s record of largely pro-union actions and Biden joining auto workers on their picket line last year. The auto union’s voice holds particular sway among blue collar voters in swing states, most notably Michigan.

Details: The union’s lobbying conference starts in Washington on Sunday. It runs through Wednesday and includes workshops for members, legislative pushes on the Hill and a reception with lawmakers on Tuesday, according to a public schedule.

The UAW and the Biden campaign on Friday declined to comment on the potential for an endorsement.

The Washington Post earlier Friday reported that the union is expected to endorse Biden.

Former President Donald Trump has also courted UAW members, paying a visit to Detroit during the strike. But he appeared at a non-union facility, and UAW President Shawn Fain has all but ruled out endorsing him.