Senator John McCain (R-AZ) speaks with reporters after voting against the "skinny repeal" health care bill on Capitol Hill in Washington, US, July 28, 2017.[Photo/Agencies]

WASHINGTON -- The US Senate rejected a bill initiated by Republicans to repeal the healthcare law known as Obamacare in a dramatic vote early Friday, blocking President Donald Trump's move to overturn his predecessor's health reforms.

Although Republicans controlled the Senate, three of them crossed party lines to join Democrats, and frustrated Trump's dream with a vote of 49 in favor and 51 against.

Senate Republicans decided to vote on the bill to repeal parts of Obamacare, which was enacted by Democrats in 2010 under former President Barack Obama, after a debate early Friday morning.

Republicans have 52 seats in the 100-seat Senate, but their efforts failed as three Republicans, Senators John McCain, Susan Collins and Lisa Murkowski, turned to Democrats.

McCain was diagnosed with brain cancer before he flew back from Arizona to cast his "no" vote to Republicans' amendment bill to Obamacare.

Trump had vowed to repeal Obamacare, also known as the Affordable Care Act, during his campaign in presidential elections.

The White House and Republicans have been struggling for months to repeal, amend or replace Obamacare.