WASHINGTON — In what’s sure to be another ratings washout, the Democratic National Committee held it’s third debate on a weekend evening, this time also pitting themselves against a major NFL game.

The timing — the Saturday before Christmas and in competition with the Jets’ 19-16 win over the Cowboys in Dallas — seemingly calculated to keep Hillary Clinton as protected as possible while assuring her challengers remain underexposed, critics noted.

At one point, Clinton came back late to the stage after an overly long bathroom break.

The moment left her two competitors cooling their heels at their podiums — a perfect illustration for the Twitter hashtag that had already started circulating hours before the debate: #hidinghillary.

“They are actively discouraging people from watching by doing it on the Saturday before Christmas. Advantage, Hillary,” Katie Packer Gage, former deputy campaign manager to Mitt Romney, told The Post. “No one hears an alternative to her. Most of America thinks there is no real primary on [the Democratic] side.”

Only 8.5 million people watched the previous Democratic debate Nov. 14. By contrast, viewership for the Republicans’ prime-time debates have ranged from 13.5 million to 24 million.

The next and fourth debate is scheduled for Jan. 17, a Sunday night.

The highlight of Saturday night’s debate came early, with Bernie Sanders apologizing to Clinton in his opening statement for accessing her confidential voter file and admitted his staff was “wrong” for taking advantage of a database breach.

“Yes, I apologize,” Sanders said.

“I want to apologize to my supporters. This is not the type of campaign that we run.

“And if I find anybody else involved in this, they will also be fired.”

Clinton, who has accused Sanders’ campaign of taking her well-researched files, accepted the public apology. “We should move on,” the Democratic front-runner said. “Because I don’t think the American people are all that interested in this.”

After the apology, the debate went on focus on plans to defeat ISIS, control guns and raise wages.

The oddest moment of the debate came when Clinton said of GOP frontrunner Donald Trump, “He is becoming ISIS’s best recruiter. They are going to people showing Donald Trump insulting Islam and Muslims in order to recruit more radical jihadists.”

There is no immediate evidence that Trump was being quoted in ISIS recruiting propaganda, the Web site http://www.politifact.com reported later Saturday.

Clinton also said, “we now finally are where we need to be,” in fighting ISIS, a remark that led Republicans — in the wake of the San Bernardino shootings and the Paris massacres — to pounce.

“No @HillaryClinton — We are not ‘where we need to be’ in the fight against ISIS,” Bush tweeted.

Clinton also pledged Saturday night to not raise taxes on people earning $250,000 or less a year. “No middle-class tax raises. That is off the table as far as I am concerned,” Clinton said.

But Sanders and former Maryland Gov. Martin O’Malley wouldn’t make that promise, citing the need for paid family and medical leave for all workers. Sanders said a small tax “$1.61 [a week] is a pretty good investment” for the benefit.

Clinton defended her stance on a no-fly zone in Syria, while Sanders’ said he has “fairly deep” differences with Clinton on US involvement in the Middle East and the backing of regime change.