"In the gloom and ugliness of this political season, one encouraging truth is often overlooked: There is a well-qualified, well-prepared candidate on the ballot. Hillary Clinton has the potential to be an excellent president of the United States, and we endorse her without hesitation," the editorial board of the Post said.
Endorsement of a candidate by major publications in the run-up to an election is a unique feature of the American democratic system.
So far almost all major US publications including The New York Times have endorsed Clinton as the next president while her Republican rival Donald Trump has failed to win even a single major endorsement.
In fact, many of the publications, which traditionally sided with Republican nominees for decades, have this time endorsed Clinton for the November 8 general election.
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"Republican presidential nominee Donald Trump is dreadful, that is true - uniquely unqualified as a presidential candidate. If we believed that Ms Clinton were the lesser of two evils, we might well urge you to vote for her anyway - that is how strongly we feel about Mr Trump. But we would also tell you that was our judgment," the Post editorial board wrote in its endorsement.
"We recognize that many Americans distrust and dislike Ms Clinton. But maybe, at this moment in history, that last weakness is also a strength. If Ms Clinton is elected, she will attempt to govern an angrily divided nation, working with legislators who in many cases are determined to thwart her, while her defeated opponent quite possibly will pretend her victory is fraudulent," it wrote.
The Post also praised Clinton for her experience on the foreign policy front.
"Her 2016 presidential campaign offers one more case study of lessons learned - a model of efficiency and of large egos subordinated to a larger cause - after her far less disciplined 2008 effort," it said.