All 46 Senate Democrats, two of their independent allies, and three Republicans - including former presidential candidate John McCain - rejected the bill in a vote held early on Friday morning.  US President Donald Trump commented that the opposing senators "let the American people down."

The so-called "skinny repeal" proposal came after Republican leaders failed to pass their version of the health care bill and failed to get enough support to repeal all of Obamacare without offering an alternative.

Read more: What is the status of Republican's Obamacare repeal effort?

The new, watered down repeal attempt was designed to target individual aspects of the 2010 Affordable Care Act - known as Obamacare - such as the requirement that everyone must get health insurance or face a fine. The proposed bill would also cancel the regulation obliging large companies to offer a health care plan to their employees and would defund the American Planned Parenthood Program for a year.

At the same time, Republican leaders devised the proposal as a stop-gap measure which would eventually allow Congress to work out a comprehensive plan to repeal and replace Obamacare. With Republicans commanding only a two-seat majority in Congress, the Friday vote leaves serious doubts about the future of that initiative.

Read more: US Senate votes to continue debate on health care reform

"This was a disappointment, a disappointment indeed," Senate Majority Leader Mitch McConnell told colleagues after the vote. "It's time to move on."

US President Donald Trump has strongly urged Republican lawmakers to repeal and replace Obamacare, recently calling it a "horrible thing" and saying the health care plan "wreaked havoc on the lives of innocent, hard-working Americans."

The pledge to repeal Obamacare was one of key promises of Trump's 2016 campaign, and the Republican party has been vocally opposing the Democrat-devised system since its introduction in 2010.

dj/msh (AP, dpa, AFP)