Donald Trump, addressing his first campaign rally on Saturday since surviving an assassination attempt, dismissed concerns that he poses a threat to America's democratic system, telling the crowd, "I took a bullet for democracy."

"I'm not an extremist at all," claimed the newly-crowned Republican presidential nominee at the Michigan rally, downplaying his reported links to Project 2025, a shadow manifesto from his close associates described by critics as an authoritarian, right-wing agenda.

He also mocked the Democratic Party, which is under unprecedented pressure for President Joe Biden to abandon his reelection bid due to concerns about his age and fitness to serve until 2029, if reelected.

"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 crowd of 12,000 supporters.

The presidential hopeful revealed that Chinese President Xi Jinping sent him a “beautiful note” following the assassination attempt.

"[President Xi Jinping] wrote me a beautiful note the other day when he heard about what happened," he said.

Trump described Xi as "a brilliant man who controls 1.4 billion people with an iron fist," adding that the Chinese leader makes people like Biden look like “babies.”

He also lauded Xi and Russian President Vladimir Putin as "smart, tough" leaders who "love their country," echoing his 2022 praise for Putin’s decision to launch a special military operation in Ukraine.

In that 2022 speech at a rally in Georgia, Trump described DPRK leader Kim Jong Un as "tough", and remarked about Kim and Xi, "The smartest one gets to the top."

On Saturday, Trump said he "got along very well" with the Chinese and DPRK leaders.

The Republican presidential nominee also voiced support for Hungarian Prime Minister Viktor Orban, agreeing with Orban's statement that "we have to have somebody that can protect us."

The Hungarian Premier was indirectly accused this week by Ukrainian President Volodymyr Zelensky of "betraying" European leaders after he traveled to Moscow for what he termed a "peace mission".

During a joint press conference with Putin, the Russian leader called on Kiev to pull back its troops and abandon its efforts to join NATO.

In his speech, the Republican recounted the moments after a gunman attempted to kill him at a rally in Pennsylvania when bloodied and surrounded by Secret Service agents, he raised a fist and urged his supporters to "fight".

Wearing a new, smaller, flesh-colored bandage over his right ear, grazed in the attack by a 20-year-old gunman who also killed one bystander, Trump described Biden as "stupid" and a "feeble old" man and called Vice President Kamala Harris "crazy" and "nuts".

The Biden-Harris campaign dismissed the speech as Trump "peddling the same lies (and) running the same campaign of revenge and retribution."

Meanwhile, Biden loyalists continued to defend the embattled president as calls for him to abandon his campaign grew louder. The 81-year-old and his team have publicly insisted that he is staying in the race, though some reports suggest discussions have begun in his inner circle about how he might step aside.

"Joe Biden is our nominee," Senator Elizabeth Warren told MSNBC on Saturday.

"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."

Read more: Trump rallies after assassination attempt; Biden isolates with COVID