In steering clear of the ideas promoted by both leading presidential candidates, Ms. Pelosi is hoping to protect the so-called front-liners who flipped Republican seats in 2018 and delivered Democrats the majority.

The speaker’s new proposal is aimed at reducing costs under the current health bill, according to people familiar with it, who insisted on anonymity to describe a plan that was not yet public. Details are still being finalized, and Ms. Pelosi — who was to meet Monday evening with Democratic committee chairs to discuss a response to the coronavirus epidemic — has not yet shared them with her rank and file. The speaker’s office declined to comment.

The plan could be unveiled as early as this week, though coronavirus could upend that timeline. In eschewing Medicare for All, Ms. Pelosi is turning away from a proposal that does not have the votes to pass the House and has divided Democrats on Capitol Hill.

Instead, the speaker is expected to propose a series of steps to make health care more cost-effective under the Affordable Care Act, including expanding tax credits and subsidies to help people buy insurance and creating a national program to help cover expenses for those with medical conditions. The plan is expected to spotlight ideas put forth by vulnerable freshmen like Representatives Lauren Underwood of Illinois and Angie Craig of Minnesota.

But Ms. Pelosi’s reluctance to embrace Mr. Sanders’s bold vision may draw the ire of her caucus’ left wing, which is pushing for a vote on Medicare for All. Her decision to shy away from the public option is especially notable, given that the House included such a system when it passed its version of the Affordable Care Act in 2009. The provision was later stripped out by the Senate.