WASHINGTON - US Senate Majority Leader Mitch McConnell conceded failure on Monday in efforts to repeal and replace former president Barack Obama's signature legislation, also known as the Obamacare, after more Republican senators joined the opposition against a GOP replacement.

"Regretfully, it is now apparent that the effort to repeal and immediately replace the failure of Obamacare will not be successful," McConnell said in a statement.

His statement came closely after two more Republican senators announced opposition on Monday against the revised Better Care Reconciliation Act, a GOP bill designed to overhaul the Obamacare.

The Senate will vote to take up the House-passed bill in coming days while calling for a repeal vote with a two-year delay for substitute, he said.

Republican Senators Jerry Moran of Kansas and Mike Lee of Utah joined two other senators in opposing the legislation, indicating that McConnell would not have the votes required to move the long-sought bill ahead.

Not long after Moran and Lee announced their defection, President Donald Trump urged Republicans in a tweet to just repeal the country's current healthcare system and work on a new plan that starts from a "clean slate".

Moran and Lee issued separate statements late Monday, saying the long-sought Republican healthcare plan will not have their support.

"We should not put our stamp of approval on bad policy," Moran said. He also urged a fresh start and "an open legislative process".

In a separate statement, Lee said the updated BCRA "doesn't go far enough in lowering premiums for middle-class families; nor does it create enough free space from the most costly Obamacare regulations".

Their opposition has marked a fatal blow for the Republicans to advance the BCRA. McConnell already postponed a vote on it Saturday in light of Republican John McCain's recovering at home in Arizona from surgery.

Before McConnell admitted failure, McCain's vote would have been decisive because of his absence set to leave Republicans short of the votes required to move forward the legislation.

The bill needs support from 50 of the 52 Republican senators to get passed, Susan Collins of Maine and Rand Paul of Kentucky have said they won't back their own party's healthcare plan.

With a unanimous opposition from Democrats and independents, the latest two defections by Moran and Lee on the bill doomed Republican attempts to get it passed.

Senate Minority Leader Charles Schumer touted the growing Republican opposition against its own bill as "proof positive" that the legislation is "unworkable".

He called on Republicans to "start from scratch and work with Democrats on a bill that lowers premiums, provides long-term stability to the markets and improves our healthcare system", instead of "repeating the same failed partisan process yet again".

"We look forward to Congress continuing to work toward a bill the president can sign to end the Obamacare nightmare and restore the quality care at affordable prices," a White House spokesman said.

Senate Republicans on Thursday unveiled a revised version of the healthcare bill in the hope of a procedural and then a final vote by senators in coming weeks amid a much-delayed GOP agenda.

The House of Representatives passed the initial version of the healthcare bill in early May, after which the bill entered the Senate for discussion.

Xinhua - Ap