MIAMI--Former President Donald Trump arrived in Miami on Monday to face federal criminal charges, while a new Reuters/Ipsos poll found a vast majority of his fellow Republicans believe the case to be politically motivated. Trump, the front-runner for the Republican nomination in the 2024 presidential election, is scheduled to be in a Miami federal courthouse on Tuesday at 3 p.m. EDT for an initial appearance in the case. Accused of unlawfully keeping U.S. national-security documents and lying to officials who tried to recover them, Trump has proclaimed his innocence and vowed to continue his campaign to regain the presidency in a November 2024 election. Trump, who turns 77 on Wednesday, touched down in Miami at 2:54 p.m. in a private jet with his name emblazoned on the side. Supporters gathered outside a nearby golf club he owns, where he was due to stay the night. "I HOPE THE ENTIRE COUNTRY IS WATCHING WHAT THE RADICAL LEFT ARE DOING TO AMERICA," he wrote on his Truth Social social-media platform before departing from New Jersey. Trump's legal woes have not affected his popularity among Republican voters. A Reuters/Ipsos poll released on Monday found that 81% of Republicans thought the charges were politically motivated. The poll also found Trump continues to lead his rivals for the party's presidential nomination by a wide margin. Some 43% of self-identified Republicans said Trump was their preferred candidate, compared to 22% who picked Florida Governor Ron DeSantis, Trump's closest rival. In early May, Trump led DeSantis 49% to 19%, but that was before DeSantis formally entered the race. Trump accuses President Joe Biden, a Democrat, of orchestrating the federal case to undermine Trump's campaign. Biden has kept his distance from the case and declines to comment on it. Republican presidential candidate Chris Christie, a former governor of New Jersey and an adviser to Trump's 2016 election campaign, was asked during a CNN townhall on Monday night if he thought the Biden Administration was weaponizing the Department of Justice against Trump. "I don't think so," Christie said. "This evidence looks pretty damning." Trump spoke to an enthusiastic crowd in Georgia over the weekend and his campaign said he would make a statement on Tuesday night, when he returns to New Jersey. With memories fresh of the Jan. 6, 2021, assault by Trump supporters on the U.S. Capitol, officials have raised security concerns. Miami police chief Manny Morales said the city was planning for a crowd size of up to 50,000 people and would close roads in the downtown area if necessary. Special Counsel Jack Smith accuses Trump of taking thousands of papers containing some of the nation's most sensitive national-security secrets when he left the White House in January 2021 and storing them in a haphazard manner at his Mar-a-Lago Florida estate, according to a grand jury indictment released last week. As special counsel, Smith, who is heading the case, is given a greater degree of independence than other Justice Department prosecutors, to try to minimize political factors. He is also investigating Trump's effort to overturn his 2020 loss to Biden. Photos included in the indictment show boxes of documents stored on a ballroom stage, in a bathroom and strewn across a storage-room floor. The indictment alleges Trump lied to officials who tried to get them back.