GRAND RAPIDS, United States: Donald Trump, holding his first campaign rally Saturday since surviving an assassination attempt, rejected concerns that he is a threat to democracy, triumphantly telling a cheering crowd: "Last week I took a bullet for democracy."

"I'm not an extremist at all," the Republican continued at the rally in swing state Michigan, dismissing his reported links to Project 2025, a shadow manifesto from figures close to him that has been characterised by opponents as an authoritarian, right-wing wish list.

And he mocked the rival Democratic Party, roiled by unprecedented pressure for President Joe Biden to abandon his reelection bid amid concerns over his age and fitness to serve, if reelected, until 2029.

"They have no idea who their candidate is... This guy goes and he gets the votes, and now they want to take it away. That's democracy," Trump told the 12,000-strong crowd of passionate supporters.

In the fiery but typically rambling speech, the Republican presidential riffed on his hardline immigration views, while espousing falsehoods about migrant crime.

He also expressed admiration for foreign autocrats including the "brilliant" Xi Jinping of China, whom he praised for controlling "1.4 billion people with an iron fist."

And he evoked the seconds after a gunman tried to kill him at a rally in Pennsylvania, when, bloodied and surrounded by Secret Service agents, he raised a fist and yelled for his supporters to "fight!"

The crowd in Grand Rapids chanted the word back to him Saturday more than once, though some appeared to tire of the lengthy address after 90 minutes and began filing out of the arena.

The rally represented a moment remarkable by any measure, with Trump back on stage exactly one week since the assassination attempt.

He appeared wearing a new, smaller, flesh-coloured bandage over his right ear, grazed in the attack by a 20-year-old gunman on a rooftop who also killed one bystander.

Security was reportedly tight inside the Van Andel Arena in Grand Rapids, Michigan, amid questions over Secret Service lapses at the Pennsylvania rally - though there were few visible signs of any greater law enforcement presence.

Meanwhile, Biden loyalists continued to defend the embattled president as the drumbeat of calls for him to abandon his campaign grows louder.

The 81-year-old and his team have remained publicly adamant that he is staying in the race, though some reports suggest discussions have begun in his inner circle about how exactly he might step aside.

There has been massive speculation over who could replace him. As vice president, Harris appears best positioned to do so.

Senator Elizabeth Warren, a leading progressive who sought the party's presidential nod in 2020, gave Harris a boost Saturday without turning her back on the president.

"Joe Biden is our nominee," she said on MSNBC. "He has a really big decision to make.

"But what gives me a lot of hope right now is that if President Biden decides to step back, we have Vice President Kamala Harris, who is ready to step up, to unite the party, to take on Donald Trump, and to win in November."

Some Democrats, however, fear that such a late switch could trigger chaos, dooming the party at the polls.

Team Trump, for its part, is effervescent after an exceptional streak of luck - from the failed assassination bid to favorable court rulings and Biden's disastrous debate performance last month.

Saturday was Trump's debut campaign appearance with running mate J.D. Vance, a 39-year-old US senator from Ohio who could help win over critical swing states like Michigan, Pennsylvania and Wisconsin.

Vance warmed up the crowd, taking a swipe at Harris.

"I did serve in the United States Marine Corps and build a business. What the hell have you done, other than collect a check?" he said of the former US senator and California attorney general.

Trump supporters had begun lining up in their dozens in Grand Rapids on Friday, nearly a full day before the rally began.

Edward Young, 64, attending his 81st Trump rally, was wearing a T-shirt showing the already iconic photo of Trump pumping his fist immediately after being shot.

"They have turned him into a martyr and left him alive," he said.

"Now he's more powerful than ever."

 -AFP