US Democrats called Friday for a giant mobilisation for abortion rights on the eve of a nationwide day of protest against an expected Supreme Court move to end federal protections for the procedure.

Multiple US organisations plan to rally Saturday, after a leaked draft ruling showed the court's conservative majority poised to overturn its landmark 1973 Roe v. Wade decision that established a right to abortion.

"I hope to see each and every one of our colleagues and the public at one of these rallies because I know we're going to turn out en masse," said Barbara Lee, a House Democrat who has in the past spoken publicly about her own back-alley abortion.

"We're not going to be denied the right to make decisions about our own bodies will not stop fighting until everyone - and I mean everyone - has access to safe, legal and accessible abortions no matter their income, their zip code or their race."

A Democratic drive to make the right to abortion the law of the land failed in the Senate on Wednesday after Republicans refused to allow a vote on the issue.

The House-passed Women's Health Protection Act would have created a federal statute ensuring access to terminations for patients nationwide -- but all 50 Republicans and one of the 50 Democrats voted not to consider the legislation.

"Once Republicans shred long-standing precedent and privacy rights, they intend to wage an all-out assault on more of our rights, including access to contraception and marriage equality," Nancy Pelosi, the top Democrat in the House of Representatives, told reporters. 

"As Republicans seek to control and criminalize women's reproductive health freedoms, Democrats are fighting to enshrine Roe v. Wade into law."

Campaigners are planning a "massive day of action" with four "anchor marches" in New York, Washington, Chicago and Los Angeles Saturday, as well as hundreds of smaller events across the country.

The groups are also urging more mobilization throughout the summer, when the final Supreme Court decision is set to be issued.