Washington, June 27 (RHC)-- Nearly two-thirds of U.S. voters think presumptive Republican presidential nominee Donald Trump is unqualified to be president, a new poll has found, underscoring that the New York businessman faces a serious popularity problem.

The ABC News/Washington Post survey released on Sunday showed that 64 percent of American voters think Trump was not fit to lead the country, while only 37 percent of the participants said the same about his rival, presumptive Democratic nominee Hillary Clinton.

In terms of overall support, Trump trails the former secretary of state 51 percent to 39 percent, snapping the race back to where it stood at March.  The real estate mogul also failed to appeal to many voters over fairness, as 66 percent of them thought he was 'unfairly biased' against groups such as women, minorities and Muslims.

This is attributable to the candidate's controversial statements against Muslims throughout the primary race, where he called for a ban on all Muslims entering the US, although he has recently withdrawn that statement.

Donald Trump has also pledged to deport millions of immigrants from the US upon becoming president, another statement that he has taken back.  Fifty-six percent of Americans participating in the poll believe that Trump is standing against their beliefs instead of standing up for their beliefs.

The Republican multi-billionaire secured the majority of delegates needed to claim the presidential nomination last month, but he continues to face opposition from many Republican officials and activists who believe he could damage the party for years to come and may cost the Republicans the White House.

On the Democratic side, Hillary Clinton was declared the presumptive nominee earlier this month after reaching the required amount of delegates.