Barb Fleming knows what it is to stand at the precipice of America’s health care system and look down. It’s a place she doesn’t want to be again.

Fleming, 58, of Bel-Nor, a self-employed sales representative, was diagnosed with stage 2 breast cancer in 2008. Upon attempting to renew her health insurance, the company wouldn’t cover the cancer because it was a pre-existing condition. This was standard industry practice at the time.

“When I called my brother to tell him I had cancer, I had to also tell him, ‘I may have to file for bankruptcy, could you help me out?’ ” Fleming recalled last week. “Literally, the weekend between lymph-node surgery and a double mastectomy, I was at (employee) orientation at a big box store because I knew I could get insurance there” through an employee health plan.

That didn’t happen — healing issues prevented her from working — and coverage through Missouri’s high-risk insurance pool took months to start. Medical bills burned through her savings. Her monthly pool-coverage premiums eventually rose above $1,200.

By 2013, though, the health care landscape had changed. Barb signed up for insurance through the Affordable Care Act — “Obamacare” — which to date has extended medical coverage to some 20 million Americans who either couldn’t afford insurance or who, like Barb, were virtually uninsurable.

Insurance companies operating under the ACA cannot refuse affordable coverage to people with pre-existing conditions. For premiums that started under $600, Barb’s cancer treatments were covered. “It brought me to a place where I could look forward to the future.”

There’s a reason the health care debate has roiled America so deeply for so long, and it isn’t because the laissez faire-ish system in place before Obamacare was working just fine — a rose-colored myth that, whether they say it or not, is Republican orthodoxy.

That’s why, after years of chanting “repeal and replace,” Republicans discovered upon fully taking power that they couldn’t repeal because they had nothing, really, to replace it with. Now they’re attempting death by a thousand cuts. This includes a suit by Missouri and 19 other red states seeking to gut the program — a slap in the face to the Barb Flemings of the world.

Obamacare offsets the inevitable losses that customers with pre-existing conditions create for insurance companies by requiring that everyone else also buy insurance, or pay a tax penalty — the much-maligned “mandate.” It’s by no stretch the best way to deliver health care, but if you’re going to insist it has to be a profit-driven system, then this or something like it is necessary.

After Republicans took control last year, Congress, in full sabotage mode, ended the tax penalty. The 20 states’ lawsuit claims this invalidates the mandate — which would mean insurance companies could no longer be expected to cover people with pre-existing conditions.

In effect, the lawsuit seeks to eliminate the legal guarantee of coverage for people like Barb.

If it succeeds, she will go back to being uninsurable in the regular market. “I can’t even imagine what my life would be like,” she said. A million or more other Missourians could be in the same situation.

Missouri Attorney General Josh Hawley, a Republican, hitched Missouri to this lawsuit. Hawley is the state’s GOP Senate nominee this year, challenging incumbent Democratic Sen. Claire McCaskill. It’s a sign of either remarkable gumption or supreme tone-deafness that he’s actually playing up health care as a campaign issue.

“I will work to get the health care reforms MO families desperately need, including protections for those with pre-existing conditions,” Hawley tweeted last month — the same Hawley, remember, who is currently suing to end a program that is the only thing protecting millions of Americans with pre-existing conditions.

He added: “We shouldn’t be holding patients hostage with Obamacare.”

I asked Barb if she feels like Obamacare is holding her hostage. She laughed. “If (the ACA) had not gone into effect,” she said, “I wouldn’t have my house anymore.”

How would Hawley cover people with pre-existing conditions? “The insurance companies can more than afford to do it,” his campaign told me last week. Wow, it was so simple this whole time! That’s not a policy, it’s a bumper sticker. Anyone who’s serious about this issue knows that just requiring such coverage from companies, with no other support structure to balance insurer’s liability, invites people to buy insurance only when they’re sick, dooming the whole system.

In other writing, Hawley has offered warmed-over Republican orthodoxy that nibbles at the edges: Allow interstate insurance sales. Bolster high-risk pools.

Go back to how it used to be.

“To walk in (to a hospital) somewhere and not have insurance … we should not be in that situation in this country,” said Barb. “Insurance should not be a privilege.”

Kevin McDermott is a member of the Post-Dispatch Editorial Board.