“They’re politicising it,” Mr Trump said at a political rally in North Charleston.
“They have no clue,” he said, adding as his backers laughed or booed: “They can’t count their votes in Iowa. … They can’t count their votes.”
He said Democrats tried to take him down with the Justice Department’s Russia election meddling probe then when House Democrats impeached him. All were unsuccessful, he claimed.
“They lost,” he contended before alluding to his rising approval ratings: “It’s all turning.”
Mr Trump was in South Carolina ahead of Saturday’s presidential primary there. He has been holding political rallies and official events the day before early primaries across the country — aiming to produce record vote totals in each state for an incumbent president and take attention away from Democratic candidates ahead of their own primary.
Former Vice President Joe Biden is expected to win his party’s primary there, but Mr Trump almost certainly will take the state against whomever his general election foe turns out to be.
He won the state by over 14 points in 2016 over former Secretary of State Hillary Clinton.
Amid worries around the country and globe about the Coronavirus outbreak, GOP Senators Tim Scott and Lindsey Graham, both of South Carolina, were spotted by television cameras near the stage. Mr Scott sang along and egged on the crowd as the song “Macho Man” played in the arena.
The president for the second time in a few hours said over 30,000 Americans die annually of seasonal influenza, but none of 15 US cases of Coronavirus have passed away.
Showing how much immigration will be a theme of his bid for a second term, Mr Trump touted his moves to ban people from countries hit hardest by the complicated virus from entering the country,=.
“Border security is health security,” he said to loud cheers.