On the campaign trail, Donald Trump showed his sharp political instincts by promising voters that no American would go without health insurance.

"I am going to take care of everybody," he said. "I don't care if it costs me votes or not. Everybody's going to be taken care of much better than they're taken care of now."

That declaration won him overwhelming support from white men and women, whose life expectancy has begun to decline.

But Trump's concept of healthcare reform ran counter to the ideological convictions of the Republicans controlling Congress.

They voted more than 60 times to repeal Barack Obama's signature legislative achievement, the Affordable Care Act. But they could not overturn it, because the president used his veto.

The law, better known as Obamacare, had been adopted without a single Republican vote when Democrats were in charge in the Capitol.

As Republicans now proceed to dismantle it - another promise to voters - Trump has given his blessing to its replacement, which is running into a wall of resistance ranging from doctors, hospitals, seniors advocates and many state governors to free-market conservatives.

Obamacare's defenders warn the Republican alternative would strip millions of patients of coverage acquired in the past few years and cost more both to taxpayers and poorer, older patients.

Conservatives, instead, call the new bill a socialist sell-out because it would continue to provide some subsidies, albeit more meager, to pay for unaffordable insurance premiums that show every sign of becoming even more expensive.

Patchwork remedies

The economics of healthcare have bedeviled many countries but America's history of patchwork remedies is particularly remarkable.

Paying for medical treatment was largely a private or charity responsibility until the 1940s.

That's when some employers began to provide insurance as a fringe benefit to evade wartime wage controls.

In 1965, the government and taxpayers emerged as a dominant factor.

READ MORE: Americans split over replacing Obamacare

The enactment of Medicare guaranteed basic doctor and hospital coverage for everyone aged 65 and older, while Medicaid helped states pay for long-term care and insurance for certain classes of the poor and disabled.

Almost 30 years later, Bill Clinton launched another presidential effort at universal coverage, in the teeth of resistance from private insurers and small business owners, who objected to requiring that they cover their employees.

His wife, Hillary Clinton, was assigned the task of designing and steering the plan through Congress. It never even was put up for a vote.

Obamacare was aimed to help fill the gap for the 16.3 percent of Americans who remained without coverage.

By the time Obama left office, the number was down to 8.6 percent, the lowest in history.

Obamacare unpopular

But Obama's seeming success has always been overshadowed by the law's unpopularity.

Many resent the requirement that every American be insured in some way, or else pay a penalty.

Yet the bigger objection derives from a fundamental reality of insurance pools - a healthy, younger majority whose premiums finance care for the far fewer who are older and sicker.

Another reality - a big redistribution of wealth through higher taxes, the financial dynamic underlying Obamacare.

Without those added taxes, paid by wealthier patients, highly profitable drug companies and - potentially - medical device makers, private insurers would see no profit and exit from the marketplace.

Republicans have pointed to another of Obamacare's flaws - the threat of too few competing insurance companies offering coverage, a sign that the system had begun a "death spiral".

But their proposed reforms have yet to address the crushing economic burden of American healthcare for too many.

It's the reason that medical bills are still a significant cause of personal bankruptcy.

Trump has made a pledge that Republican legislators have been too cautious to repeat - that not only would everyone be protected by insurance, but that the cost of premiums for everybody would fall.

Yet long before Trump became a successful Republican politician, he argued that the solution for his country's dilemma was the popular system across the northern border, where it's the government, not private insurers, that pay the doctors and hospitals.

"Doctors might be paid less than they are now, as is the case in Canada," Trump wrote in one of his books back in 2000, "but they would be able to treat more patients because of the reduction in their paperwork. The Canadian plan also helps Canadians live longer and healthier than Americans."

Why doesn't he believe that any longer?

"It could have worked in a different age," he said on his climb to the presidency.

But he's never explained why not now.