United Auto Workers union President Shawn Fain will join President Joe Biden on the picket line Tuesday in Wayne County, Michigan, according to a source familiar with the situation. The source provided no specifics about the exact location.

The UAW, however, is not involved with former President Donald Trump's planned visit on Wednesday, nor have they been in contact with his team, the source said, and there has been no official invitation to Trump.

Trump will skip the second Republican presidential primary debate in California Wednesday and is expected to also head to Michigan to address union workers.

The United Auto Workers union is on strike against General Motors, Ford and Stellantis, the first time in its history that it has struck all three of America's unionized automakers at the same time. The strike began on September 15, with targeted strikes at one facility at each of the Big Three automakers.

Negotiations between the striking UAW and Ford remained very active over the weekend and on Monday, but there is still distance on some key issues. There has not been the same movement and seriousness of progress with both General Motors and Stellantis, the source added.

On Friday, UAW said it was expanding its strike against GM and Stellantis but said that progress in negotiations with Ford means it won't expand the number of Ford workers on the picket lines.

Fain said Friday "all parts distributions centers at General Motors and Stellantis will be on strike. We will shut down parts distribution until those two companies come to their senses and come to the table with a serious offer."