Former vice president Joe Biden in Pittsburgh on April 29. (Saul Loeb/AFP/Getty Images)

IT SAYS something about the state of the two major political parties that, while Washington was focused on President Trump’s racist tweets and his strategy to divide for political advantage, Democratic presidential candidates were engaged in an increasingly substantive debate about the future of health care. No matter how you feel about former vice president Joe Biden’s plan to build on Obamacare, which he released Monday, or Vermont Sen. Bernie Sanders’s Medicare-for-all proposal, which he defended in a speech Wednesday, the Democratic field has already far surpassed Mr. Trump in seriousness. His “plan” to this day has not progressed beyond a promise to destroy Obamacare.

Of course, you get only so many points for effort. Substance is key — and while some of the plans are prudently progressive, others are ideological flights of fancy.

On the wildly unrealistic side is Mr. Sanders’s plan, which Sen. Elizabeth Warren (Mass.) also supports. Mr. Sanders would eliminate private insurance and enroll everyone in a government-run plan that is, in fact, far more generous than Medicare. Even if Americans wanted to give up their private insurance, Mr. Sanders’s plan to eliminate premiums, co-payments and other cost-sharing, while offering Americans a massive suite of free benefits, would either be unimaginably expensive or force unsustainably huge cuts in payments to doctors and hospitals. Mr. Sanders points to other countries with “single-payer” systems to prove that building one in the United States is possible. In fact, other nations are far less generous than what Mr. Sanders proposes.

Mr. Biden, meanwhile, would improve the Affordable Care Act, which itself built on the existing system. He would offer all Americans the option of buying into a “public option” health plan structured like Medicare. This resembles Colorado Sen. Michael F. Bennet’s “Medicare-X” public option plan and the systems Sen. Amy Klobuchar (Minn.) and former representative Beto O’Rourke (Tex.) favor.

Mr. Biden would make the public option free for low-income Americans in states that did not expand their Medicaid programs to cover them. This plan would fill some of the gaps left by the Affordable Care Act; Mr. Biden’s campaign says it would cover 97 percent of Americans.

Other candidates have attempted to have it both ways, genuflecting before the dream of Medicare-for-all while also supporting less radical plans. South Bend, Ind., Mayor Pete Buttigieg supports “Medicare for all who want it” — essentially Mr. Biden’s public option — but argues that this would “create the glide path toward Medicare for All,” as Americans chose the public option over private plans. Sens. Cory Booker (N.J.) and Kirsten Gillibrand (N.Y.) co-sponsored Mr. Sanders’s bill but stop short of calling for private insurance to be abolished. Sen. Kamala D. Harris (Calif.) also co-sponsored Mr. Sanders’s bill, but she has sent confusing signals about where she stands on the role of private insurance.

The Democratic field is showing more respect for voters than Mr. Trump did when he turned in a blank page during the 2016 campaign. But as voters consider their choices, they should ask themselves who is offering something feasible — and who is selling something else.