The paper’s editorial board wrote on Friday that Trump was no longer a Republican problem but a challenge the entire nation must now confront.
“The real estate tycoon is uniquely unqualified to serve as president, in experience and temperament,” it said. “He is mounting a campaign of snarl and sneer, not substance. To the extent he has views, they are wrong in their diagnosis of America’s problems and dangerous in their proposed solutions.”
“Trump’s politics of denigration and division could strain the bonds that have held a diverse nation together. His contempt for constitutional norms might reveal the nation’s two-century-old experiment in checks and balances to be more fragile than we knew,” the paper added.
The condemnation came a day after Trump formally accepted the Republican nomination, saying the paper would not endorse the billionaire businessman. “A Trump presidency would be dangerous for the nation and the world.”
The harsh language of the Post’s editorial was a departure from its traditional approach of waiting until later in the race to weigh in on presidential candidates.
The newspaper added that its condemnation of Trump did not serve as an endorsement of his Democratic rival, Hillary Clinton. “We have criticized the presumptive Democratic nominee, Hillary Clinton, in the past and will do so again when warranted.”
In June, Trump denounced the Post as “dishonest” and said its coverage was “incredibly inaccurate.”
A nationwide survey published by Reuters on Friday found that Trump was narrowing the gap with Clinton in the wake of the Republican National Convention (RNC), trailing her 41-38 percent.
Trump's campaign has been marked by controversy from the start, including disparaging remarks about women, immigrants and Muslims.