Obamacare: Mike Pence breaks tie, Senate rejects first Republican amendment

Democrats are united against the bill, saying it would end healthcare coverage for millions

US Senate Republicans have voted in favour of a floor debate on their efforts to re-write healthcare policy, with Vice President Mike Pence breaking the tie.

The Senate on Tuesday decisively rejected a Republican proposal to repeal-and-replace Obamacare as Senator John McCain returned from Arizona to applause from fellow senators to cast a critical vote for Republicans, CNN reported.

The floor debate will on Wednesday morning continue to overhaul the Affordable Care Act, even though there are no guarantees the votes are there to eventually pass the bill.

Two GOP senators -- Susan Collins and Lisa Murkowski -- sided with all Democrats in