WASHINGTON — Democratic governors are threatening to sue the Trump administration over a proposed rule that would force Planned Parenthood to give up its federal grants or keep family-planning and abortion-related services under different roofs.

"If this reckless policy is finalized as written, we will have no choice but to explore all possible avenues, including legal options, to block it from harming the women in our states," Washington Gov. Jay Inslee and 13 fellow members of the Democratic Governors Association wrote in a letter to Health and Human Services Secretary Alex Azar. "Our voices will be heard on this damaging proposal, and we are prepared to match our words with action."

Health and Human Services Secretary Alex Azar delivers remarks on reducing drug costs at the White House on May 11, 2018. Nicholas Kamm / AFP - Getty Images file

Earlier this month, the Trump administration announced that it would develop a new rule governing so-called Title X family-planning funds to make it harder for providers of abortions and related services to obtain federal money. While it is already illegal to use taxpayer funds for abortion, Planned Parenthood and similar groups use federal grants for other women's health care services while using private money for abortion-related services — often at the same facilities and with the same personnel.

Conservatives applauded Trump for targeting Planned Parenthood's funding — the rule would force family-planning groups to give up either federal money or their ability to refer patients for abortion. But abortion-rights activists say it's an unconstitutional infringement on women's rights that will disproportionately affect poor women.

In their letter, the Democratic governors appealed to Azar to abandon the proposed rule to avoid legal action.

"This dangerous proposal would upend decades of bipartisan cooperation, taking away women’s healthcare through trusted medical providers like Planned Parenthood and eroding their access to comprehensive, medically accurate information," the governors wrote. "We strongly urge you to reconsider this plan, which is nothing more than a domestic 'gag rule' that poses serious risks to women’s health."