Donald Trump is set to return to the campaign stage, if not the campaign trail, on Saturday with a rally in Sarasota, Florida.

There are no national elections in the US this year but the former president maintains a grip on the Republican party ahead of the 2022 midterms and is toying with a run for the presidency in 2024, despite gathering legal problems in New York and elsewhere.

On Thursday, the Trump Organization and its chief financial officer, Allen Weisselberg, pleaded not guilty to criminal charges brought by the Manhattan district attorney, regarding suspected tax fraud.

Trump accused the prosecutors of being politically motivated, saying: “The Republican party should not allow this to happen. It’s a radical left disgrace to our country, and nobody should stand for it – not even Democrats. Republicans must fight back. This will rip our country apart!”

But his refusal to leave the political stage is seen by many as dangerously divisive itself. Trailing coverage of the Sarasota event, Trump told supporters it could be “seen on OAN and Newsmax” – two hard-right TV networks.

The rally was billed as a Fourth of July celebration featuring fireworks and was expected to draw several thousand in a state Trump won by more than three points in 2020.

Trump lost that contest to Joe Biden by more than 7m ballots nationally and by 306-232 in the electoral college, a conclusive beating – which he called a landslide when it was in his favour over Hillary Clinton in 2016 – which he nonetheless claims was the result of electoral fraud.

It was not but Trump’s lie dominates the Republican party, fueling the deadly assault on the US Capitol on 6 January and attempts in GOP-controlled states to limit ballot access and make it easier to overturn election results.

This week, Trump told the Fox News host Sean Hannity he had decided on whether to run again in 2024, saying: “It’s not that I want to. The country needs it. We have to take care of this country. It isn’t fun, fighting constantly, fighting always.”

He also trailed “a significant announcement about his efforts to protect Americans’ first amendment rights”, which he said he would make at his golf course in Bedminster, New Jersey, on Wednesday.

According to Reuters polling, 53% of Republicans believe Trump won the election and blame his loss on illegal voting. A quarter of the public think Trump won.

Earlier this week, Trump visited the US-Mexico border and accused Biden of neglecting national security. He held his first comeback rally last weekend in Wellington, Ohio, supporting a former White House aide’s primary challenge to Anthony Gonzalez.

Gonzalez was one of the 10 House Republicans who voted to impeach Trump on a charge of inciting the 6 January attack – Trump’s second impeachment, a unique achievement.

Trump has promised to campaign against all 10 House Republicans who voted to send him to trial in the Senate. Seven Republicans there voted for his guilt – not enough to convict.

In Ohio, he rehashed old lines and repeated his lie about the election, claims the Utah senator Mitt Romney compared to professional wrestling: “entertaining” but “not real”.

Many Republicans believe them. One attendee in Ohio, Gary Bartlett, 65 and a retired manual worker at General Motors, told the Guardian he voted for Democrats until he switched to Trump in 2016. He also said the 2020 election was stolen.

“There were too many things on TV showing polling places and too many rumours,” he said. “When I drive around Ohio and other states I see Trump signs everywhere. There’s no way Biden could have got that many votes.”

Ahead of the Florida rally, Jack Brill, chair of the Republican party of Sarasota county, told Reuters he hoped Trump would galvanize supporters ahead of the midterms and a gubernatorial race in which a prominent Trump supporter, Ron DeSantis, will seek a second term.

Significant numbers of Republican voters see DeSantis as an appealing option for 2024. The 42-year-old has been at the fore in Republican-led fights against anti-coronavirus lockdowns, racial justice protests and expanded ballot access.

In a straw poll of potential 2024 candidates at a conservative conference in Denver in June, DeSantis finished ahead of Trump, 74% to 71%. DeSantis’ office has said he is focused on winning re-election in Florida.

DeSantis will not be attending Trump’s rally in Sarasota. His office said he planned to spend the weekend in Surfside, where rescuers have spent more than a week searching for survivors in the rubble of a condo building collapse that killed at least 22 and left dozens missing.