Andy Burnham (L) was set to get the keys to No. 10 Downing Street just 28 days after being sworn in as a Member of Parliament after winning the Makerfield by-election, a seat the sitting lawmaker vacated specifically to enable Burnham to make a run for the prime ministership.File photo by House of Commons/EPA

July 14 (UPI) -- Newly elected Labour Member of Parliament Andy Burnham was set to become British prime minister uncontested at the beginning of next week after securing unassailable backing from fellow lawmakers.

On Tuesday, with two days of the nomination period for the leadership of the party still to run, the former Mayor of Greater Manchester had the support of 349 Labour MPs, making it a mathematical impossibility for another candidate to overtake him.

Candidates need the backing of 81 Labour MPs minimum to be nominated -- equivalent to 20% of the party's 403 lawmakers -- but the level of support Burnham has means insufficient numbers of uncommitted MPs remain to nominate another candidate.

Endorsements he needs from three other affiliated groups, including two trade unions, were expected to be rubber-stamped.