WASHINGTON (CBS / AP) — House Minority Leader Nancy Pelosi is declining to endorse Sen. Bernie Sanders’ universal health care bill.

The liberal California Democrat says that while she has long supported the idea the bill captures, of everybody getting health coverage, “Right now I’m protecting the Affordable Care Act.”

She also disputes the idea that the Vermont independent’s bill has become a litmus test for Democrats, forcing them to prove their ideological purity by getting onboard.

Several Senate Democrats who are seen as potential presidential candidates in 2020 have endorsed Sanders’ bill, including Elizabeth Warren of Massachusetts and Cory Booker of New Jersey.

Sen. Kamala Harris (D-California) was the first senator to co-sponsor the bill. Speaking at a town hall meeting in Oakland last month, Harris endorsed Sanders’ proposal, saying that “health care is a right.”

Harris went on to say on her website that the legislation is the “morally and ethically right thing to do” and that it makes sense “from a fiscal standpoint.”

I'm co-sponsoring @BernieSanders' Medicare for All bill because health care is a right. Add your name if you agree: https://t.co/pD7PtYj4ZF — Kamala Harris (@KamalaHarris) August 31, 2017

Sanders’ bill would in effect expand Medicare to cover all Americans, not just the elderly.

Pelosi says President Barack Obama’s Affordable Care Act is actually more comprehensive than Medicare.

TM and © Copyright 2017 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2017 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.