The scale of the Republican Party’s lying about their health care policy is, as Sarah Kliff writes, stunning.

The Republican Party is driving legislative and judicial efforts to gut protections for people with preexisting conditions that are now the law of the land. At the same time, they are running ads about their commitment to protecting people with preexisting conditions that feature the very elected officials suing to negate those protections, and President Donald Trump is saying, well, this:

Republicans will totally protect people with Pre-Existing Conditions, Democrats will not! Vote Republican. — Donald J. Trump (@realDonaldTrump) October 24, 2018

That’s not exaggeration. It’s not spin. It’s not misleading. It’s a lie. It’s pure up-is-downism. It’s a flagrant foul committed against reality. It’s scandalous, and it should be treated as a scandal. As Sarah notes, 14 percent of voters say protecting people with preexisting conditions is their top priority. The essence of elections is that voters have a clear idea of what the two parties intend to do so they can make an informed choice between them. The fact that the president is trying to utterly deceive them is important.

But there’s another question all this raises: Why are Republicans spending so much time lying about their health care policy? Why not just adopt the popular protections for preexisting conditions they claim to support? How did Republicans get here?

I have a theory.

A bit of health policy history is necessary here. In the early 2000s, it looked like Democrats and Republicans were converging around an approach to health care both could live with, built atop some of the Republican ideas offered in response to Bill Clinton’s 1994 proposal.

These Republican proposals, in a bid to show that costs could be contained using regulated markets and individual responsibility, included an individual mandate alongside regulations stopping insurers from discriminating against the ill or the old. The theory was that you brought everyone into the market and forced insurers to compete for their business by offering higher-quality plans at lower costs, not by separating the healthy from the unwell.

Mitt Romney passed a plan based on those ideas in Massachusetts, and it worked pretty well. Democrats looked at that plan and saw a compromise they could live with, so it became the base of the 2008 proposals from Hillary Clinton, John Edwards, and Barack Obama (though Obama initially omitted the mandate). Obama was elected president and tried to pass that plan into law.

Republicans, under Mitch McConnell and John Boehner’s leadership, decided they had to unite against Obama’s proposal, and so they turned completely on ideas they had once supported. The scale of the about-face was stunning: A bunch of GOP senators voted for a resolution calling the individual mandate unconstitutional even though they were still, at that very moment, co-sponsors of the Wyden-Bennett Healthy Americans Act, which included an individual mandate.

“I would characterize the Washington, DC, relationship with the individual mandate as truly schizophrenic,” Sen. Ron Wyden (D-OR) told me with some wonder.

Over the next decade, opposition to Obamacare became the central feature of Republican policy thought. This had two downstream consequences. One was that it wrecked the central political theory behind the Obamacare compromise — that Democrats, in giving up the policy advantages of single-payer, would gain the political benefits of bipartisan support — and sent Democrats toward Medicare-for-all, which is better at cutting costs, simpler to explain, and more difficult to challenge legally.

The other was that it forced Republicans to abandon a basically reasonable vision of health care policy and left them with, well, nothing. Opposing Obamacare isn’t a policy vision, but it had to be made into one, and so Republicans tried: They began attacking Obamacare’s weak spots — its high premiums and deductibles — and proposing to lower them by permitting insurers to once again discriminate against the sick and the old.

Deregulating the insurance market so healthy people could pay less for skimpier, higher-deductible care at the expense of their older, sicker neighbors — many of whom would now be uninsurable again — was not what people were asking for. But it’s what Republicans ended up embracing. It was all they had left. Every time they inched toward more popular ideas, like retaining protections for people with preexisting conditions, they quickly found themselves forced to support something too close to Obamacare.

The problem with the Republican health care vision is that it’s hideously unpopular; that’s why the GOP’s Obamacare replacement efforts collapsed. And it’s left Republicans with two choices. They can level with the public about their health care plan and lose the election or they can lie to the public about their health care plan in a bid to keep their jobs. So far, they’ve chosen lying.