On the stump, Donald Trump promised to repeal and replace the Affordable Care Act. Now obstacles are emerging on the left and right.

Democrats are sowing panic, falsely predicting that more than 20 million will lose coverage. Newly designated Senate Minority Leader Chuck Schumer claims Trump will “rue the day” ObamaCare is repealed.

Meanwhile, on Trump’s right flank, House Republicans are pushing Medicare “reform” and taxes on workers’ health benefits — unpopular ideas that will undermine Trump’s political support and derail his agenda.

Here’s the real deal about repeal.

Will 20 million lose coverage?

Not even close: 16 million of those who gained coverage are enrolled in Medicaid, the public program for low-income residents. ObamaCare allowed states to expand the category of those eligible to sign up for Medicaid, with the federal government covering the tab.

Repeal could result in less federal funding. But no one is pushing to abolish the nation’s health-safety net. And states that just expanded Medicaid are unlikely to do a 180 and shrink it. The 16 million are likely safe.

President-elect Trump is proposing giving states more flexibility in how Medicaid is managed. That’s urgently needed. Federal Medicaid spending has shot up 40 percent in the last three years. And research shows that extra spending isn’t improving patients’ health.

What about the other nearly 5 million newly insured? They’re in ObamaCare plans, along with another 6 million who already had insurance, and all of them are having a tough time. Technically, they’re “covered,” but many can’t come up with the cash to see a doctor. They’re struggling with exorbitant deductibles — $6,000 per person for the typical bronze plan.

In short, about 5 million previously uninsured people — not the bogus 20 million — may need help after repeal. Trump is proposing market reforms to lower costs and increase choices for consumers stuck in the individual market.

Will people with pre-existing conditions lose out?

No. All the GOP replacement plans protect them, but not through the cynical, coercive scheme that ObamaCare used.

Obama forced two groups of people into the same insurance pool: the healthy and the chronically ill. Healthy people would pay premiums but never meet their sky-high deductibles.

Instead, their premiums would foot huge medical bills for the chronically ill, who consume 10 times as much medical care. Healthy people saw it was a scam. They refused to sign up, despite the penalty.

ObamaCare architect Ezekiel Emanuel says forcing the healthy to enroll is essential. Sorry — there’s a fairer way. Trump would allow insurers to charge sick people more, then subsidize these “high risk” customers with taxpayer dollars. That spreads the cost fairly over the whole population, instead of burdening people in the individual market.

Voila: Premiums and deductibles will drop fast for people in the individual market.

Is President Obama right that the law is working far better than its critics say? Nope. More than 200 million have been hurt by it. Count them: 155 million with employer-provided plans whose deductibles have soared thanks to the ACA, plus the 11 million paying ACA penalties for not enrolling, plus hundreds of thousands of part-time workers whose hours were slashed by employers dodging the mandate and 55 million seniors harmed when Medicare was cut to bankroll ObamaCare.

Is this the time to change Medicare?

No way. House Speaker Paul Ryan and Budget Committee Chairman Tom Price want Medicare “reform” this spring. But candidate Trump promised to replace ObamaCare, fund infrastructure, cut taxes and fix immigration. Not change Medicare.

A Medicare battle could torpedo his agenda. Remember the demagogues who vilified Ryan in 2012 with images of granny going over the cliff in a wheelchair?

Ryan and Price also want to cap the tax exemption on employer-provided health plans. That would betray union workers who for years have swapped raises for lavish tax-free health benefits. These workers just gave Trump his remarkable win.

Trump made the election a referendum on ObamaCare. Republicans in Congress need to respect the voters and make Trump’s agenda the priority.

Betsy McCaughey is a senior fellow at the London Center for Policy Research.