US President Donald Trump has said he will "never forget" those people who failed to endorse him during his presidential election campaign.

The Republican made the comment during a meeting with Michigan governor Rick Snyder, who did not back Trump during the race.

The president joked: "Come, governor, even though you didn't endorse me!" as he met with the lawmaker to discuss manufacturing plans in the state, The Hill reports.

His comment was echoed by Elaine Chao, the secretary of transportation, who told Snyder: "He hasn't forgotten."

Trump replied: "I never forget."

The president has previously suggested he is no fan of people who failed to endorse him during his campaign – with Snyder suggesting he had not been the first person to have received such a comment from the president.

Reflecting on Trump's words, Snyder reportedly said: "I mean, he's made that comment about quite a few people.

"So I view it as something that, let's move forward, let's build bridges and let's make a stronger economy in our country," the Detroit News reported.

Snyder did not endorse any of the candidates during the 2016 election – and did not back Trump once he had secured the GOP nomination.

House speaker Paul Ryan was among others who took a long time to endorse Trump, with the ongoing feud between the pair apparently ending only after Trump won the 2016 election.