Gordon Brown has refused to quit despite his ruling Labour party facing meltdown in the European elections in the light of fresh MPs expenses claims.The embattled British prime minister pledged to clean up politics on Sunday with a new code of conduct for Members of Parliament. With the latest opinion polls putting Labour in third place behind the Liberal Democrats for the first in 22 years, it could be Balls for Darling. The secretary of State for schools Ed Balls, close aid to Brown, is rumoured to be hot favourite to take over from current Chancellor of the Exchequer Alistair Darling. The opposition Tory leader David Cameron looks set to romp home in Thursday’s election. He has also had to defend his own expenses claims after it was suggested he could have saved taxpayers money on a second home mortgage. Cameron has called for a plan to enable voters to sack their MPs. One poll puts Labour on 17 percent and facing the possibility of slipping to forth place behind the eurosceptic UK Independence Party.