Former US president Donald Trump has hinted at a possible run for president again in 2024, attacked his successor Joe Biden, and repeated his fraudulent claims that he won the 2020 election in his first major appearance since leaving the White House nearly six weeks ago.

“Our movement of proud, hard-working American patriots is just getting started, and in the end we will win. We will win,” Mr Trump said in a highly anticipated speech at the Conservative Political Action Conference in Orlando, Florida, on Monday (Australian time).

Still refusing to admit he lost the November 3 presidential election to Mr Biden, Mr Trump offered a withering critique of his Democratic successor’s first weeks in office and suggested he might run again.

“They just lost the White House,” the Republican former president said after criticising Mr Biden’s handling of border security.

“But who knows, who knows, I may even decide to beat them for a third time.”

During Mr Trump’s tumultuous final weeks in office, his supporters launched a deadly attack on the US Capitol on January 6 in an attempt to block Congress from certifying Mr Biden’s election victory, a win that Mr Trump falsely claimed was tainted by widespread fraud.

A civil war has erupted within the Republican Party with establishment figures such as Senate minority leader Mitch McConnell eager to put Mr Trump in the rearview mirror and others, including Trump ally Senator Lindsey Graham, believing the party’s future depends on the energy of the pro-Trump conservative base.

Mr Trump declared the Republican Party was united and said he had no plans to try to launch a third party, an idea he has discussed with advisers in recent months.

“We’re not starting new parties. We have the Republican Party. It’s going to be united and be stronger than ever before. I am not starting a new party,” he said.

The results of a straw poll of CPAC conference participants gave Mr Trump a strong show of support with 55 per cent saying they would vote for him in the 2024 Republican presidential nomination race. Florida Governor Ron DeSantis was runner-up, with 21 per cent.

Without Mr Trump, Mr DeSantis led the field with 43 per cent, and other potential Republican candidates had single digits.

But not everyone supported Mr Trump. A separate question on the poll asked whether Mr Trump should run again in 2024 – getting a mixed result, with 68 per cent saying he should run and 32 per cent opposed or having no opinion.

“It’s tough to get seven out of 10 to agree on anything,” pollster Jim McLaughlin told CPAC in explaining away the results.

Still, Trump fervour at the four-day CPAC event has been so strong that Mr Trump’s eldest son Donald Trump Jr. declared it “T-PAC” and participants rolled out a golden statue of the former president.

In the short term, he is making plans to set up a super PAC political organisation to support candidates who mirror his policies, an adviser said.

Starting his speech more than an hour late, Mr Trump said he wanted to save the culture and identity of the United States.

He sought to position himself as the lead critic of the new president, including on immigration and security along the US border with Mexico, and the slow reopening of schools closed due to the pandemic.

“Joe Biden has had the most disastrous first month of any president in modern history,” Mr Trump said.

Recent polls have given Mr Biden a job approval rating well past 50 per cent, a strong showing from Americans.

The Biden White House has made it clear it plans to ignore Mr Trump’s speech.

“Our focus is certainly not on what president Trump is saying” at CPAC, White House spokeswoman Jen Psaki said last week.

-AAP