John McCain: I cannot 'in good conscience' vote for new Republican healthcare plan

US Senator John McCain has declared his opposition to the last-ditch effort to repeal and replace "Obamacare", dealing a likely death blow to the legislation and, perhaps, to the Republican Party's years of vows to kill the programme.

It was the second time in three months 81-year-old Mr McCain emerged as the destroyer of his party's signature promise to voters.