Bernie Sanders plans to crank up the pressure on his 2020 Democratic primary rivals over health care.

During a speech Wednesday advocating for "Medicare for All," the Vermont independent will urge all Democratic presidential candidates to reject money from the insurance and pharmaceutical industries. He will push the field of about two dozen not to "knowingly" accept donations greater than $200 from political action committees, lobbyists or "top executives" for the industries, the Sanders campaign said.

"If we are going to break the stranglehold of corporate interests over the health care needs of the American people, we have got to confront a Washington culture that has let this go on for far too long," Sanders will say, according to his campaign. "That is why I am calling on every Democratic candidate in this election to join us in rejecting money from the insurance and drug industries. Candidates who are not willing to take that pledge should explain to the American people why those interests believe their campaigns are a good investment."

Sanders has long pushed for a government run, single-payer health insurance system to offer comprehensive coverage to all Americans. He has contended the system will not only cover more Americans and cut their health costs, but also root out corruption and inefficiencies in the private health industry.

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But as a means to stand out in a crowded field, single-payer has lost some of its luster for Sanders as it gains traction within the party. Four of Sanders' primary competitors — Sens. Cory Booker, D-N.J., Kirsten Gillibrand, D-N.Y., Kamala Harris, D-Calif., and Elizabeth Warren, D-Mass. — co-sponsored the Medicare for All bill he introduced earlier this year.

By calling on his rivals to reject drug and insurance company money, Sanders aims to distance himself again on health care — which voters consistently rank among their top concerns. It also fits into a broader strategy within the Democratic field: Many candidates have railed against large individual contributions or corporate donations, arguing they corrupt the political process.

It was not immediately clear how much the industry executives, lobbyists and PACs have given to 2020 Democratic candidates so far. Candidates filed their financial disclosures for the second quarter, the first major fundraising period for some contenders, earlier this week.

Sanders' remarks Wednesday come as he faces more pressure over his support for Medicare for All. Former Vice President Joe Biden — who has led most early national and state polls in the race — slammed the single-payer proposal while outlining his health care plan on Monday.