Almost two-thirds of Americans believe Donald Trump committed crimes before he was elected, a poll has found.

Forty-five per cent of US voters think the president has even broken the law since entering the White House, compared to 43 per cent who do not, according to Quinnipiac University’s survey.

Tim Malloy, assistant director of the poll, said the results “deliver a double-barrelled gut punch” to Mr Trump’s integrity.

The research also found Americans believe Mr Trump’s former lawyer Michael Cohen – who is headed to jail for fraud, tax evasion and lying to congress – is more honest than the president.

Half of voters said they believed Cohen’s allegations about Mr Trump’s “unethical and illegal behaviour,” compared to 35 per cent who thought the president’s denials were true.

Will Trump fall to the 25th Amendment? The key players in the debate Show all 7 1 /7 Will Trump fall to the 25th Amendment? The key players in the debate Will Trump fall to the 25th Amendment? The key players in the debate President Trump Donald Trump, whose firing of the FBI director James Comey in 2017 sparked concerns among senior government officials Getty Will Trump fall to the 25th Amendment? The key players in the debate James Comey The former director of the FBI, James Comey, whose firing by Mr Trump sparked the crisis in 2017 EPA Will Trump fall to the 25th Amendment? The key players in the debate James McCabe James McCabe, the former acting director of the FBI, who has made the explosive accusations in a TV interview AFP Will Trump fall to the 25th Amendment? The key players in the debate Rod Rosenstein The deputy attorney general Rod Rosenstein, who allegedly discussed which cabinet members might back invoking the 25th Amendment Reuters Will Trump fall to the 25th Amendment? The key players in the debate Lindsey Graham Republican senator Lindsey Graham, a key Trump ally who has pledged to hold an investigation into the affair AFP Will Trump fall to the 25th Amendment? The key players in the debate Christopher Wray The new director of the FBI, Christopher Wray, who took over after Mr Trump fired Mr Comey AP Will Trump fall to the 25th Amendment? The key players in the debate Mike Pence The vice-president Mike Pence, who has dismissed suggestions Mr Trump is not capable of discharging his duties AFP

Cohen has claimed Mr Trump took part in a criminal conspiracy to cover up extramarital affairs during his election campaign, and has also accused him of "lies, racism and cheating" during explosive congressional testimony last week.

Sixty-four per cent of Americans believe the president committed crimes before he was elected in November 2016, found the Quinnipiac poll, compared to 24 per cent who said he did not.

"When two-thirds of voters think you have committed a crime in your past life, and almost half of voters say it's a tossup over whether you committed a crime while in the Oval Office, confidence in your overall integrity is very shaky," Mr Malloy said.

"Add to that, Michael Cohen, a known liar headed to the big house, has more credibility than the leader of the free world."

The poll found a third of Republicans believed Mr Trump had committed crimes before becoming president, while 48 per cent thought he had not.

Respondents of every other party surveyed, as well as every gender, education, age and racial group, said by wide margins that Mr Trump was a criminal.

Support free-thinking journalism and attend Independent events

Doubts about Mr Trump’s integrity did not extend to calls for him to be removed from office; only 35 per cent felt he should be impeached, compared to 59 per cent who said he should not be.

Voters gave the president negative 38-55 per cent job approval rating, a deterioration from 38-57 per cent in a Quinnipiac poll in January.