Now that President Trump has survived his first 100 days, a burning question in Washington is whether House Speaker Paul Ryan will survive the second 100 days. A miracle might be needed.

Ryan’s repeated inability to pass anything resembling a repeal of ObamaCare goes beyond simple failure. It’s shaping up as a potential disaster for the Trump presidency and the GOP congressional majority.

With every Republican talking about little else for seven years, and with Trump in the White House, producing a repeal-and-replace bill should have been relatively low-hanging fruit.

But Friday’s second collapse of the effort suggests Ryan can’t deliver the GOP’s majority caucus. And if he can’t deliver it to drive a stake in ObamaCare, why should anyone think he can deliver it for tax reform or immigration, both of which will be even more contentious among Republicans?

And if he can’t deliver his majority for anything significant, why is he the speaker?

The noisy doubts about Ryan’s ability are quite a comedown. Not so long ago, he represented the fresh-faced future of the Republican Party.

He was a rising star and policy wonk, so appealing that Mitt Romney tabbed him as his 2012 running mate at the age of 42.

Ryan’s performance was adequate, and when then-Speaker John Boehner lost control of the Republican majority in 2015, Ryan was something of a consensus pick to succeed him. He was initially reluctant because the job required more travel to members’ districts, and because it meant he would have to cede turf on policy and devote himself to herding cats to pass legislation, whatever the details.

Tellingly, one of the criticisms of his tenure is that Ryan hasn’t fully embraced the job’s duties. He played a heavy role in writing the ObamaCare repeal legislation, kept it secret from most members and then expected universal support when he released it.

He was so overconfident that he assured Trump he had the votes. But he didn’t, and the bill was pulled at the last minute.

That was more than a defeat for Trump, who wasted considerable capital supporting the plan and twisting arms. It was an embarrassing blot on the president’s first 100 days.

The consequences for Ryan have been stark, too. It was a reminder that, for all his promise, the glorious things he would someday achieve have proved elusive. ­Already in his 10th congressional term and third year as speaker, talk of his vast potential is being replaced by rumbling suspicion that he is all talk.

Ryan, affable and gregarious, is given to preachy pronouncements. He labels his agenda “a better way,” a phrase so anodyne as to be meaningless.

Newt Gingrich, the most important Republican speaker of the modern era, said recently at a Gatestone Institute lunch that Ryan is making the transition to leading a governing majority, as opposed to leading a House majority with a Democrat in the White House.

It’s a fair point and a nice way to describe the learning curve. In his own defense, Ryan says the big-ticket items he and Trump both want, including legislation to ­rebuild the military, are a 200-day project.

Yet that approach conveys a sense of business-as-usual in Washington, which is distinctly at odds with the mood of Trump Nation. And the failure to make any clear progress on those big items at the halfway mark is ominous.

Democrats, of course, are doing all they can to run out the clock so they can use gridlock to hammer Republicans in the 2018 midterms. If they succeed, the GOP could lose the House and Rep. Nancy Pelosi would be speaker again.

In that scenario, the Trump presidency would be hobbled, especially on its domestic agenda of creating jobs, economic growth and border control. The chance to reverse the worst of the Obama regulatory overreach would be curtailed, and Democrats would have momentum to unseat Trump in 2020.

Ryan and the president have an odd bedfellows relationship growing out of the bruising campaign, though they try to hide the strains. But Ryan often asserts his independence, which fuels suspicion that he’s too much of a Washington Republican to share Trump’s populist convictions about how to help the working class.

For his part, Trump showed some frustration in a Friday interview with Martha MacCallum on Fox News, saying he’s “disappointed” that House Republicans haven’t gotten more done.

Of Ryan, Trump said he’s “trying very, very hard,” which sounds like a compliment you give while handing out a participation trophy.

At this stage and with these stakes, trying isn’t good enough. Ryan needs to succeed soon, or give somebody else a chance.

Tourists drawn to Euro terror?!

A poll finds that 42 percent of American adults are less likely to visit Europe because of the spate of terror attacks, while 45 percent say the attacks will have no impact on their plans.

Both views are reasonable — but get this: 7 percent say the attacks make them more likely to travel to Europe. Who are those people and what the hell are they thinking?

A plague on housing

As metaphors for waste and incompetence go, it will be hard to top the finding that nearly 900 apartments are vacant in a city affordable-housing program. Some have sat empty for more than a decade.

With homelessness soaring and City Hall throwing money at new projects and shelters, it is mind-boggling that 38 percent of the units in the Tenant Interim Lease program have no tenants.

Public Advocate Letitia James uncovered the scandal, which she called “shocking.” It is — if you are naive about government bureaucracies.

The buildings were essentially abandoned by their landlords decades ago, and the city allowed tenants to manage them with the promise they could buy their apartments for as little as $250 each.

But reports say squatters have taken over buildings and that some tenant-association funds have been looted. Meanwhile, renovations have gone on endlessly, leaving many apartments vacant.

This is an extreme version of a common snafu. Rather than manage what they have, bureaucrats find it easier to squander vast sums of money on new programs. But the old programs never die, so taxpayers pay twice for the same shoddy service.

It’s called doing less with more, and nobody does it better than government.

Candid camera

With about 50 police officers in Washington Heights wearing body cameras, the NYPD is starting a pilot project ordered by the court. Naturally, the political class embraces it, with most city pols sharing a distrust of the cops expressed by a Manhattan fan of the cameras. “Finally, someone is going to keep an eye on them,” Joel Perez told a reporter.

Fair enough, but I repeat my suggestion: It would be far more enlightening if Mayor de Blasio and members of the City Council wore body cameras. Imagine what we’d learn about malfeasance then.