Newly announced Democratic presidential candidate Cory Booker said Friday he wouldn’t do away with private insurance, even as he supports “Medicare for all,” wading into one of the hot-button issues of the 2020 presidential campaign.

The New Jersey lawmaker in 2017 said he supported fellow Sen. Bernie Sanders’ Medicare for All Act, a measure that would have created a single-payer health system and eliminated private insurance.

Asked on Friday if he’d do away with private insurance, Booker replied: “Even countries that have vast access to publicly offered health care still have private health care, so no.”

Booker’s comment came the day he announced his campaign, and followed remarks by fellow Sen. Kamala Harris, who made headlines this week by saying expanding Medicare to all Americans could mean eliminating private health-insurance plans. An adviser to Harris later said the California Democrat and presidential candidate would be open to plans that would preserve the health-insurance industry.

Another 2020 contender, Sen. Elizabeth Warren of Massachusetts, joined Harris in co-sponsoring Sanders’ 2017 bill. But Warren dodged a question about banning private health insurance in an interview with Bloomberg.

Booker, Harris and Warren are part of a crowded Democratic field that includes nearly two dozen declared or potential contenders.

As the Democrats’ primary season heats up, Harris moved up in a Politico/Morning Consult poll released earlier this week.

But pundits say it’s too early in the season for polls to mean much of anything, and note Warren gets plaudits for other issues.

“Warren is wonky but liberal activists love her tax plan,” said University of Virginia political scientist Larry Sabato.

Related: Bernie Sanders proposes big hike in estate taxes, after Elizabeth Warren floats wealth levy

Greg Valliere of Horizon Investments said it’s too early for specific issues and that “voters need to hear some Trump bashing first, specifics second.” He said “a long discourse on Dodd-Frank won’t make much of a difference right now,” referring to the financial-reform law Warren supported.

Warren is expected to formally announce her candidacy on Feb. 9, and may expand on her health-care ideas then. It may be her best opportunity yet to connect with mainstream voters.

“Even though Elizabeth Warren is a professor and has released a tax plan, she styles herself a plain talking’ Oklahoma populist tiling against Wall Street and the fat cats,” Prof. Bruce Schulman of Boston University told MarketWatch.