The overwhelming majority of Americans now believe that President Biden was in some way involved in his son Hunter’s overseas business dealings and helped him make millions of dollars from his clients, according to a new poll. The survey also finds that President Trump has a higher approval rating than the incumbent and leads in polling nationally — even in multi-candidate fields. 

On Tuesday, Harvard University and the Harris Poll released the results of their April 2024 survey of American voters, showing that Mr. Biden fares poorly on his job performance and election prospects. His perceived involvement in his son’s business schemes is a view held even by a sizable number of Democrats. 

The poll finds that 58 percent of Americans believe the president was involved in those business deals, while 42 percent say he was not involved. Nearly 90 percent of GOP voters believe that he was involved, while 36 percent of Democrats also hold that view. 

When asked about the first son’s legal troubles, 74 percent of voters say he is likely guilty of tax evasion. He was charged with several counts of failing to report and pay his taxes between 2016 and 2019. Those charges carry a maximum penalty of 17 years in federal prison. 

A majority of Americans also believe, according to the poll, that Mr. Biden is too old and incompetent to serve as president. In total, 55 percent of voters say he is not mentally fit for the position, while 66 percent say he is simply too old. They also say — to the tune of 64 percent — that his “public lapses” are growing “more frequent” by the day, and 60 percent call “fair” those questions about his age and fitness for the presidency.

Voters also question Mr. Trump’s own potential criminality, though to a lesser degree. Among all voters, 55 percent say he has “committed crimes,” and 52 percent say he is a “threat to democracy” if elected again. 

Nearly one-third of Democrats say that their own partisans are using the justice system unfairly against Mr. Trump. Among all voters, 57 percent think he is being targeted by Democrats, and 43 percent say he is being treated fairly. In total, 31 percent of Democratic voters say that Democrats are weaponizing the justice system. 

Concerns about Mr. Biden’s involvement in his son’s alleged crimes and the president’s fitness for office are weighing on his ability to win the general election, according to the poll. Mr. Trump leads Mr. Biden in a head-to-head race and leads among a multi-candidate field when all major third-party candidates are included in the survey. 

In the two-man race, Mr. Trump leads the incumbent president by five points, 48 percent to 43 percent, with 9 percent undecided. When undecided voters were asked to choose which candidate they are leaning toward, Mr. Trump leads by four points, 52 percent to 48 percent. When Robert F. Kennedy Jr. is included in the survey, Mr. Trump leads with 45 percent and Mr. Biden takes 41 percent, while Mr. Kennedy takes 14 percent of the vote. 

Mr. Trump’s largest polling lead comes in the five-candidate field, which includes Messrs. Trump, Biden, and Kennedy, as well as an independent candidate, Cornel West, and a Green Party candidate, Jill Stein. In that poll, Mr. Trump takes 46 percent while Mr. Biden takes 40 percent of the vote. Mr. Kennedy wins 12 percent, Mr. West takes 2 percent, and Ms. Stein takes 1 percent.