Rep. Greg Walden got an earful during his town hall meeting in Medford Friday morning, not least about his key role in efforts to repeal and replace the Affordable Care Act. Walden handled the volatile situation with aplomb, but he may have a harder time when he returns to Washington, D.C., where the most conservative wing of his caucus is focused on dismantling the health care system entirely, including removing key protections for policyholders that Walden says he wants to keep.

Complicating the picture even further is President Donald Trump's threat to withhold federal subsidies that help pay the premiums for many insured Americans, among them a large proportion of Walden's own 2nd District constituents.

In his role as chairman of the House Energy and Commerce Committee, the panel tasked with considering health care reform, Walden was one of the chief authors of the American Health Care Act, the plan intended to replace what has become known as Obamacare. The AHCA would have covered fewer Americans and benefited higher-income people at the expense of those at the other end of the economic scale. The plan never came to a vote because too many House Republicans refused to support it — the conservative Freedom Caucus because it didn't completely repeal Obamacare, and more moderate Republicans because they feared a backlash from constituents who wanted to keep their newly acquired coverage.

The AHCA did preserve some key features of Obamacare, including the requirement that insurers cover people with pre-existing conditions and a ban on insurers charging seriously ill people higher premiums than healthy ones. Walden says he supports retaining both elements, but conservatives in his caucus have proposed letting states get around the ban on higher premiums, which could price sick people out of the market.

Walden says he'd have to be convinced that people with pre-existing conditions would have the same quality and affordability of coverage they have now before he would support changing the stalled legislation.

Meanwhile, Trump is forcing the issue with his threat to withhold subsidies to insurers under the existing system. As columnist Dana Milbank explains on this page, it doesn't really matter whether the president follows through. Just the threat is enough to spook jittery insurance companies into leaving the health insurance exchanges. A system that was functioning, despite Trump's claims to the contrary, now likely is doomed to fail.

In his Medford town hall Friday, Walden said, "We need to do more on saving the market as the Obamacare exchanges are collapsing before our eyes."

They aren't yet, but thanks to Trump, they probably will. On Wednesday, Trump said his threat to end the subsidies would bring Democrats to the table to negotiate a replacement for Obamacare. But he doesn't need Democrats. He needs Republicans, among them Greg Walden, to agree on what the replacement should look like.