Sometimes in business you need to be willing to walk away in a negotiation. When I was CEO of a health insurer, I canceled our contract with a major pharmacy chain when it wouldn’t negotiate prices. But first we made sure the downside risk was acceptable for our policyholders. That’s how business-to-business (B2B) relationships often work and frequently this tactic is successful, as it was for us. I imagine that President Trump’s threats to lenders and contractors in the past were similar and were effective.

But in developing a competitive market where you are trying to entice many players into a long-term commitment, confidence and cash flow are critical. This is the situation now in the Obamacare exchanges under the Affordable Care Act, where these underpinnings of trust are in question. It is most definitely not the place for hard-nosed B2B negotiation Donald Trump knows so well. And his latest bombshell — this week’s threat to withhold cost-sharing subsidies for the working poor who buy Silver plans — is exactly the opposite of what he should be doing.

There are two critical considerations facing insurers right now. First, the ones that still remain in the individual exchanges have to decide whether to submit their 2018 plan designs and premiums by May 23. Second, the law continues to force them to set premiums for the key Silver plans based on the cost-sharing reductions in the law. But without the promised subsidies to help the working poor with their out-of-pocket expenses, insurers will have to eat the difference.

Even the possibility of such an event will force them to either raise their Obamacare premiums for next year by 20%, according to the Kaiser Family Foundation, or just drop out.

An already uncertain insurance world has just become untenable thanks to President Trump’s misreading of the nature of this fragile market. This is a time for reassurance, not threats. Even if he thinks that political posturing may work to persuade Democrats to work with him—an unlikely result—it will work to the detriment of any long-term solution.

Faced with this hostile gesture, my guess is that virtually every health insurer still in the market will exit by simply not filing their plans for next year. Nothing is making them stay except the potential for profit and acceptable risk—both of which are questionable now.

Without their participation, millions of people who now rely on the ACA exchanges will be left with no choices and suffer the consequences.

Even worse would be an immediate end to these cost-sharing subsidies. Then insurers, whose 2017 premiums were set under the assumption that the government would do what it had promised, would still have to honor their contracts with subscribers but would suffer massive losses. The ensuing chaos would collapse the stock of investor-owned plans who were foolish enough step forward to meet this social need and would trigger defaults, bankruptcy and, at a minimum, financial distress for everyone else.

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The irony is that suggested replacement options for the ACA, including the Republicans’ American Health Care Act (AHCA)—apparently still in play even after its recent failure—-all depend on the same set of insurers to continue competing for enrollees, albeit under a different set of subsidies and rules.

Why any CEO would trust the flawed political process to foster a stable business environment is beyond my comprehension. Even Paul Ryan’s Medicare reform in his Way Forward Republican plan for health care would face similar trust issues.

The insurance industry won’t play Charlie Brown to President Trump’s Lucy and have the football yanked away time after time. In the last two years, Congress reneged on the ACA promise of normal risk-reduction backup in the startup period, paying only 12% of what was promised. The proposed AHCA replacement threatens major reduction in premium subsides. This third threat will be too much. Insurers will just drop the mike and exit stage right.

While others in the administration are trying to avoid this by extending deadlines and reassuring continuing current support to stabilize the market, Trump’s misreading of the market may damage the exchanges beyond repair and, with it, the continued role of private insurers in future government options.

J.B. Silvers is a professor of health finance at Case Western Reserve University.