Donald Trump on Tuesday night announced his candidacy for the Republican presidential nomination in 2024, likely sparking another period of tumult in US politics and especially his own political party.

“In order to make America great and glorious again, I am tonight announcing my candidacy for president of the United States,” Trump said from ballroom of his private Mar-a-Lago Club in Palm Beach, Florida, where he stood on a stage crowded with American flags and Make America Great Again banners.

Vowing to defeat Joe Biden in 2024, he declared: “America’s golden age is just ahead.”

The long-expected announcement by a twice-impeached president who incited a deadly attack on Congress seems guaranteed to deepen a stark partisan divide that has fueled fears of increased political violence.

But it also comes as Trump’s standing in the Republican party has suddenly been put into question. Trump spoke at Mar-a-Lago a week after midterm elections in which his Republican party did not make expected gains, losing the Senate and seeming on course for only a narrow majority in the US House.

In his remarks, Trump took credit for Republicans’ performance victory in the House, even though they are poised to capture a far narrower majority than anticipated. “Nancy Pelosi has been fired. Isn’t that nice?” he said. The Associated Press has not yet projected which party will win the majority.

In a party hitherto dominated by Trump, defeats suffered by high-profile, Trump-endorsed candidates led to open attacks on the former president and calls to delay his announcement or not to run at all. As Trump’s standing has slipped, Ron DeSantis, the governor of Florida, has surged into strong contention after sailing to reelection last week.

Trump’s announcement also coincided on Tuesday with the release of Mike Pence’s memoir, So Help Me God, in which the ex-president’s once-faithful lieutenant criticizes him for his conduct on January 6. The former vice-president is also maneuvering toward a possible 2024 run despite falling out of favor with the Maga base.

Brushing past Republican setbacks in 2022 and his defeat in 2020, Trump insisted that he was the only candidate who could deliver a Republican victory in 2024.

“This is not a task for a politician or a conventional candidate,” he said. “This is a task for a great movement.”

His third candidacy comes as he faces intensifying legal troubles, including investigations by the justice department into the removal of hundreds of classified documents from the White House to his Florida estate and into his role in the 6 January attack. Trump has denied wrongdoing and used the attacks to further his narrative that he has been unfairly targeted by his political opponents and a shadowy “deep state” bureaucracy.

“I’m a victim,” Trump said, making reference to the Russia investigation and the raid on his Mar-a-Lago estate.

On Tuesday, Trump nevertheless pressed forward with his run.

Painting a bleak portrait of the United States, with “blood-soaked” city streets and an “invasion” at the southern border, Trump said his campaign was a “quest to save our country.”

In the less than two years since Biden took office, a period Trump referred to as “the pause”, he accused his successor of inflicting “pain, hardship, anxiety and despair” with his economic and domestic policies.

Trump offered an alternative vision, which he called the “national greatness agenda”. Among the policy proposals he endorsed on Tuesday were the death penalty for drug dealers, term limits for members of Congress and planting an American flag on Mars. And wading into the social fights he enjoys inflaming, Trump promised to protect “paternal rights” and keep transgender athletes from competing in women’s sports.

Though he made no explicit mention of his stolen-election lies, he promised to overhaul the nation’s voting laws, vowing that a winner would be declared on election night. In close contests, it can take several days before enough votes are tabulated in a state to project a winner, but Trump and his allies have seized on the delay to spread baseless conspiracy theories about results.

Despite promising to deliver remarks as “elegant” as the gold-plated room he was standing in, Trump’s rambling, hourlong speech turned to name-calling and ridicule, lashing the “fake news”, mocking the former German chancellor Angela Merkel’s accent and accusing Biden of “falling asleep” at international conferences. At one point, he appeared to confuse the civil war with the reconstruction period that followed and scoffed at climate science.

Without acknowledging his 2020 defeat, Trump insisted that beating Biden in 2024 would be much easier because “everybody sees what a bad job has been done.”

He called Biden the “face of left-wing failure and government corruption” and accused him of worsening inflation and “surrendering” America’s energy independence. He also slammed the administration’s withdrawal from Afghanistan as “the most embarrassing moment in the history of our country”.

“Our country is being destroyed before your very eyes,” he said, casting his four years in office as a glowing success, despite leaving behind a nation shaken by disease and political turmoil.

Now 76, Trump was long seen as a colorful if controversial presence in American life, a thrice-married New York real-estate mogul, reality TV star and tabloid fixture who flirted with politics but never committed.

But in 2015, after finding a niche as a prominent voice for rightwing opposition to Barack Obama – and a racist conspiracy theory about Obama’s birth – Trump entered the race for the Republican nomination to succeed the 44th president.

Proving immune to scandal, whether over personal conduct, allegations of sexual assault or persistent courting of the far right, he obliterated a huge Republican field then pulled off a historic shock by beating the Democratic nominee, Hillary Clinton, in the 2016 election.

Trump’s presidency was chaotic but undoubtedly historic. Senate Republicans playing political and constitutional hardball helped install three supreme court justices, cementing a dominant rightwing majority which has now removed the right to abortion and weakened gun control laws while eyeing further significant change.

Trump’s third supreme court pick, replacing the liberal justice Ruth Bader Ginsburg with Amy Coney Barrett, a hardline Catholic, came shortly before the 2020 election. That contest, with Obama’s vice-president, Joe Biden, was fought under the shadow of protests for racial justice and the coronavirus pandemic, the latter a test badly mishandled by Trump’s administration as hundreds of thousands died.

Trump was conclusively beaten, Biden racking up more than 7m more votes and the same electoral college win, 306-232, that Trump enjoyed over Clinton, a victory Trump then called a landslide.

But Trump’s refusal to accept defeat, based on his “big lie” about electoral fraud, fueled election subversion efforts in key states, the deadly January 6 attack on the US Capitol by supporters and far-right groups, a second impeachment for inciting that insurrection (and a second acquittal, if with more Republican defections) and a deepening crisis of US democracy.

With a third White House bid, Trump hopes to defy political history. Only one former president, Grover Cleveland, has served two nonconsecutive terms. Cleveland was elected in 1884 and 1892, but, unlike Trump, he won the popular vote in the intervening election of 1888.

Trump flirted with announcing a new run throughout Biden’s first two years in power, ultimately delaying until after midterm elections, which did not go as he or his party expected. But while high-profile backers of Trump’s stolen election myth were defeated, among them his choice for Arizona governor, Kari Lake, more than 170 were elected, according to the Washington Post.

Until his midterms reversal, Trump dominated polling of potential Republican nominees for 2024. His closest rival in such surveys, DeSantis, reportedly indicated to donors he would not compete with Trump. But the landscape has now changed. DeSantis won re-election by a landslide, gave a confident victory speech to chants of “two more years” and has surged in polling – prompting attacks from Trump. At least one Republican mega donor, Ken Griffin, has said he backs the Florida governor.

Should Trump dismiss DeSantis as he has so many other challengers and win the nomination, the 22nd amendment to the US constitution would bar him from running again in 2028. But a rematch of 2020 remains possible. Though Biden will soon turn 80 and has faced questions about whether he should seek a second term himself, he is preparing a re-election campaign.