Mr. Ryan is right that the Obamacare market has endured hardships. It isn’t as competitive as many of its advocates had hoped, and shoppers in many parts of the country have only one insurer to choose from. Prices, which were lower than expected in the first few years of the program, spiked this year by an average of 22 percent across the country. There have also been some high-profile exits from insurers like Aetna, UnitedHealth Group and most recently Humana. Rural counties have been particularly hard hit.

But those recent woes are not the same thing as a death spiral, a technical term used to describe a complete market failure in which premiums spiral upward so only the sickest customers buy coverage.

Growing evidence suggests that the markets, despite their problems, are far from collapse. Because of how the current subsidies work, people were generally shielded from this year’s higher prices, and enrollment has remained steady. Several recent analyses argue that this year’s increase was a market correction, and that a smoother market would follow in the years ahead.

Many insurers had been struggling to make money but now seem closer to breaking even, said Deep Banerjee, an analyst with Standard & Poor’s.