U.S. Sen. Ed Markey, medical experts and pro-choice advocates slammed the Trump administration's proposed changes to the Title X program on Tuesday, arguing that withholding federal funds from centers that provide or refer abortion services "would turn back the clock" on women's rights and reproductive health.

The federal Title X program offers federal grants to support family-planning services for low-income patients across the country. However, a new rule floated last year and finalized earlier this month by the administration would cut off those funds for any provider that performs abortions or makes abortion referrals.

At a press conference held at a Planned Parenthood clinic in Boston, Markey called the proposed change "disastrous."

"From the halls of the Supreme Court to the halls of local health centers, the Trump administration is waging an all-out assault on women's reproductive health," Markey said. "A woman's reproductive health decision should be left up to a woman and her health care provider. That is it. A health care provider receiving federal funds should be judged on its ability to serve a patient. That is it."

Attorneys general in 21 states, including Massachusetts' Maura Healey, joined Planned Parenthood and the American Medical Association in a federal lawsuit challenging the rule, which is set to take effect in May. Markey said members of Congress also plan to file legislative amendments aimed at blocking the proposed change.

In 2017, Massachusetts providers received more than $6 million in Title X funds for services that covered about 75,000 residents, officials said at the press conference.

"Providing a patient with all the relevant information and options within the context of a confidential, trusting relationship is an obligation for physicians, one that we don't take lightly," said Dr. Carole Allen, a trustee with the Massachusetts Medical Society. "To strip from a physician the ability to provide all needed information to a patient is unconscionable."