Teamsters' support for Biden but not for Harris didn't go unnoticed by former TMZ host and producer Van Lathan, who suggested racism played a role in the union's decision to not endorse a candidate this year.

"So when Joe Biden ran in 2020 the Teamsters endorsed. Biden-Harris was then the most pro union administration ever, yet support eroded when Harris was top of ticket," Van Lathan tweeted. "What changed I wonder???"

Chris Towler, who is a political science professor at Sacramento State University, tweeted the straw poll results showing support for Biden prior to him dropping out and new support for Trump when matched up against Harris. He opined that it was "no surprise the first Democratic candidate in almost 40 years to not get their endorsement is also the first woman of color to lead a major party ticket."

"And miss me with the whole 'her policies' sh—, just a few months ago the Biden-Harris policy agenda had Teamsters’ support," Towler wrote.

Towler wasn't the only political science professor to say racism among the union's rank-and-file was the motivation for the Teamsters' non-endorsement. University of South Carolina poli-sci professor David Darmofal insinuated it was the only reason that made sense. Demographic data compiled by Zippia from the U.S. Census Bureau and the Bureau of Labor Statistics found that the Teamsters' workforce is 73 percent male, and 60 percent white.

"White man Biden runs in 2020: The Teamsters and Pope Francis are incredibly friendly toward him. Black woman Harris runs in 2024: The Teamsters and Pope Francis are not incredibly friendly toward her," he tweeted. "What's your alternative explanation? There is none."

James Williams — a former advisor to Sen. Dick Durbin (D-IL) — also suggested a racial element was at play. He lamented that the fourth largest labor union in the United States "won’t support a black woman for the [White House] whose policies support your very right to organize vs her opponent," adding: "In the real world, that’s just straight up being a bunch of bigots."

Others commented that the Teamsters' announcement made even less sense when considering the Biden-Harris administration's openly pro-union record. As journalist Lauren Burke pointed out, Biden and Democrats in Congress voted for a $36 billion package included in the 2021 American Rescue Plan that saved the Teamsters' pension fund (with Harris actually casting the tie-breaking vote in the U.S. Senate).

The Biden-Harris administration has also strengthened the National Labor Relations Board (NLRB) to help the Teamsters bolster their own ranks. According to More Perfect Union producer Jordan Zakarin, Biden's NLRB ruled earlier this month that Amazon's approximately 275,000 delivery drivers were to be classified as employees, allowing Teamsters to have the ability to organize them under their umbrella.