Former US President Donald Trump meets with leaders and members of the International Brotherhood of Teamsters at their headquarters on January 31, 2024 in Washington, DC. — AFP

Former US President Donald Trump expressed his confidence Wednesday that Teamsters will vote for him, as the Republican hopeful prepares for a showdown with Democrat Joe Biden. 

After meeting with the union leaders in Washington, Donald Trump said: "So we had a very productive meeting with a lot of Teamster representatives."

The meeting of the 77-year-old with the International Brotherhood of Teamsters came as he attempts to gain the support of the union from Joe Biden ahead of their rematch in November.

Republicans are not much friendly to labour organisations, but many of their conservative social policies have been able to resonate with rank-and-file union members at the ballot box even as labour leaders have generally endorsed Democrats.

"A big part of the voting bloc votes for me — a very big part... nobody knows what the exact number is — but some people say more than 50% of the Teamsters vote for me," the four-time indicted former president said.

Biden — sometimes nicknamed "Union Joe" — was endorsed last week by the United Auto Workers (UAW) and describes himself as the most pro-union US president ever.

That backing earned the UAW president Shawn Fain an angry rebuke from Trump, who called the labor leader a "dope."

The business mogul Trump is leading former South Carolina governor Nikki Haley comfortably after the two opening contests in the Republican primary and is expected to be anointed as the party's standard-bearer at its convention in July.

Victory in November though will require him to win back much of the support he hemorrhaged to Biden in 2020 in the all-important swing states of the Midwest — the working class heartland of American manufacturing.

Trump is not expecting to receive the Teamsters' endorsement, as the union went with Biden in 2020, praising the Democrat's "long history of standing with unions and workers on the job site."

Trump said: "Stranger things have happened. Usually, a Republican wouldn't get that endorsement — usually, they only do Democrats. But my case is different as I've employed thousands of Teamsters."

Teamsters president Sean O'Brien described the conversation as "pleasant" and "direct," telling reporters that the former president and a group of officials discussed workers' rights, bankruptcy reform and other union priorities.

O'Brien added that the 81-year-old incumbent president has also committed to a meeting and his members had "more questions" of both candidates.

He said his Teamsters would typically reveal who they are backing after the summer party conventions but added that "the endorsement or non-endorsement may come sooner than later. We haven't made a decision."