WASHINGTON - US Democratic presidential nominee Hillary Clinton surged to a broad advantage against her Republican rival Donald Trump in the latest ABC News/Washington Post poll, with two-thirds of Americans seeing him as biased against groups such as women, Muslims, and a new high, 64 percent, call the billionaire businessman unqualified to serve as president.

These and other doubts about Trump have produced a sharp 14-point swing in preferences among registered voters, from +2 points for Trump in mid-May, after he clinched the Republican nomination, to +12 points for Clinton now, 51-39 percent. That snaps the race essentially back to where it was in March.

Analysts attributed his alienation from fellow Republicans and large majorities of voters overall in the course of a month of self-inflicted controversies that propelled Clinton to a double-digit lead nationally.

The survey finds sweeping unease with the presumptive Republican nominee’s candidacy - from his incendiary rhetoric and values to his handling of both terrorism and his own business - foreshadowing that the November election could be a referendum on Trump more than anything else.

Roughly two in three Americans say they think Trump is unqualified to lead the nation; are anxious about the idea of him as president; believe his comments about women, minorities and Muslims show an unfair bias; and see his attacks on a federal judge because of his Mexican American heritage as racist.

A slimmer majority say they disapprove of the way Clinton has handled questions about her use of a personal email server while she was secretary of state, and half of Americans are anxious about the prospect of a Clinton presidency, underscoring the historic unpopularity of the two major-party candidates. In fact, so strong is many Americans’ opposition to Clinton and desire for a change in Washington that even some registering their disapproval of Trump say that as of now they feel compelled to vote for him.

Nevertheless, in a head-to-head general election matchup, Clinton leads Trump 51 percent to 39 percent among registered voters nationwide, the poll found. This is Clinton’s largest lead in Post-ABC polling since last fall and a dramatic reversal from last month’s survey, which found the nearly even, with Trump at 46 percent and Clinton at 44 percent.  As the hard-fought general election gets underway, Trump’s political standing is on dangerous ground. Fifty-six percent of the public at large say the celebrity business mogul stands against their beliefs, while 64 percent say he does not have the necessary credentials to be president. Fifty-six percent feel strongly that he is unqualified.

 Nearly one-third of Republicans and Republican-leaning independents say Trump is unqualified for office, and 18 percent say he does not represent their beliefs, exposing deep fissures in the GOP base as Trump struggles to unite conservatives going into next month’s national convention in Cleveland.  Then there are the Americans who plan to vote for him despite their disapproval. For instance, 18 percent of people who found Trump’s comments about the judge racist, 15 percent of those who think his comments generally are biased against women, minorities or Muslims, and 11 percent of those who think he is unqualified say they support Trump over Clinton.

  Trump enjoys a big lead with those who want a new direction for the country, 64 percent to Clinton’s 26 percent. After eight years of President Barack Obama, a majority of Americans, 56 percent, say they want to elect a president who can set the nation in a new direction. Forty-seven percent say they feel so strongly. 

The poll, conducted in the immediate aftermath of a massacre in Orlando that was perpetrated by a man who reportedlypledged allegiance to the Islamic State, showed Obama’s approval rating at 56 percent - its highest level in Post polling since May 2011, after the killing of Osama bin Laden.

Obama is more popular now than Republicans George W. Bush and George H.W. Bush in the waning months of their presidencies. Although Obama’s approval rating has not reached the level of former Democratic president Bill Clinton’s in 2000, his standing suggests that he could be a relatively effective surrogate for Hillary Clinton on the campaign trail.

The survey of 1,001 randomly selected adults found a slight uptick in the share of people who identify as Democrats, from 33 percent in May’s poll to 36 percent this month. Self-described Republicans accounted for 24 percent of those polled this month, ticking down from 25 percent in May, while independents made up 33 percent. This shift in party identification, however, accounts for less than half of Clinton’s gains in the new poll.

In May, Trump was more competitive with Clinton because he had just secured the Republican nomination and the party’s electorate was coalescing around his candidacy.

Clinton’s unfavorable ratings among registered voters tied their record high last month, matching Trump’s at 57 percent and weighing her down.

But that dynamic reversed over the past month, with Democrats unifying behind Clinton and Republicans expressing fresh doubts about Trump. While 88 percent of Democrats or Democrat-leaning independents say they support Clinton, a smaller 79 percent of Republican-leaning voters back Trump.