The former US president told a crowd in Iowa, that he will “very, very, very probably do it again” in 2024.
Mr Trump was speaking at the first of four rallies in five days as he campaigns for Republican candidates in next week’s midterm elections.
US President Joe Biden is also travelling across the country to get out the vote.
Neither Mr Biden nor Mr Trump is on the ballot next Tuesday when American voters will decide the balance of power in the US Congress and key state governorships.
But the midterms will set the US political landscape ahead of the presidential election in two years’ time.
“I ran twice,” he said. “I won twice, and did much better the second time than I did the first, getting millions more votes in 2020 than I got in 2016.
“And likewise, getting more votes than any sitting president in the history of our country by far.
“And now in order to make our country successful, and safe and glorious. I will very, very, very probably do it again.”
“Very soon,” he told the cheering crowd. “Get ready.”
Mr Trump did win the most votes ever – 72 million – for a sitting president in 2020, but still lost to the challenger, Mr Biden, a Democrat, who pulled in 81 million.
Mr Biden – who campaigned on Thursday in New Mexico and California – has reportedly been meeting senior advisers to plan his potential 2024 re-election campaign, setting up a possible rematch with Mr Trump.
For his part, Mr Trump has teased for months about a potential third campaign for the White House.
In October, he told a rally in Texas: “I will probably have to do it again.” In Pennsylvania in September, he said: “I may just have to do it again.”
Mr Trump’s former senior counsellor, Kellyanne Conway, said earlier on Thursday at an event in Washington DC that her former boss would “announce soon” about his possible presidential plans.
She said she gave Mr Trump credit for resisting the temptation to declare a White House run already this year, as it would have distracted from Republican candidates in the midterms.
If he does run in 2024, he may not go unchallenged within his party.
Potential Republican rivals include Mr Trump’s former Vice-President Mike Pence and Florida Governor Ron DeSantis, among others.