Former longtime Teamsters President Jim Hoffa blasted his successor on Thursday for the unions controversial decision not to endorse Kamala Harris for president.

Hoffa accused the unions current leader, Sean OBrien, of a failure of leadership, saying the Teamsters non-endorsement would boost the campaign of former President Donald Trump. He called it a critical error on OBriens part.

There is only one candidate in this race that has supported working families and unions throughout their career, and that is Vice President Kamala Harris, he said in a statement sent to reporters.

Hoffa, the son of Jimmy Hoffa, headed the union for 23 years before stepping down in 2022. He said he oversaw the presidential endorsement process six times during his tenure.

In every case, we supported the candidate that demonstrated a proven track record of fighting for working Americans and unions, Hoffa said.

OBrien announced Wednesday that the 1.3-million-member Teamsters would not be endorsing Harris or Trump, saying the union found no definitive support among members for either partys nominee. The union also released internal polling the same day showing members preferred Trump to Harris.

The announcement from the international union angered progressive members and prompted a slew of its local affiliates to declare their backing for Harris.

As of Thursday afternoon, 11 Teamster locals and joint councils had endorsed the Democrat within a 24-hour span, including some in the swing states of Pennsylvania, Michigan and Wisconsin, according to a tally provided by the Harris campaign.

Asked for a response to Hoffas comments, Teamsters spokesperson Kara Deniz provided a statement calling the former union leader an armchair quarterback.

The Teamsters Union lost hundreds of thousands of members under Hoffas failed leadership, the union said. As we successfully build back that member density under Sean OBrien, we will continue to support and respect all our members Democrats, Republicans, and Independents.