Britain's political leaders planned to campaign through the night on Tuesday in a final push for votes, two days before a parliamentary election that opinion polls suggest will be the closest in nearly 20 years. Prime Minister Gordon Brown's Labor party, in power since 1997, trails the opposition Conservatives by seven or eight points before the May 6 vote, according to the latest polls. That could give David Cameron's centre-right party a slim majority in parliament or leave him just short of taking overall control of the lower house, depending on how the votes are spread across Britain's 650 electoral districts. Cameron, keen to end his party's 13 years in opposition and secure a solid majority, will campaign overnight on Tuesday, seeking support from the third of voters said to still be undecided. Brown, expected to match Cameron's unprecedented campaign marathon, said he would “take full responsibility” if Labor loses on Thursday, but stressed his centre-left party was still in the race. “I still think there are thousands of people who have still to make up their minds,” Brown said in an interview with GMTV, a breakfast television programme. His attempt to win a fourth consecutive election for Labor was undermined by one of his candidates who described him in a local newspaper interview as “the worst prime minister ever”, in part due to his crime and immigration policies. Manish Sood, standing for election in Norfolk, eastern England, told Sky News he stood by his comments: “All the policies he is bringing in are a total disaster.” The Financial Times newspaper gave Cameron a boost, switching its support from Labor to the Conservatives. It said Cameron's party will be better at tackling Britain's record budget deficit and the recovery from the worst recession since World War Two. “We are taking absolutely nothing for granted,” George Osborne, the Conservatives' finance spokesman and election co-ordinator said in a message to supporters. “I want us to fight to persuade every single voter that is still undecided.” Two of Brown's senior ministers appeared to appeal to centre-left Labor supporters in some close-fought electoral districts to consider voting for the third party, the Liberal Democrats, to undermine the Conservatives. Welsh Secretary of State Peter Hain said Labor voters in marginal seats where either the Lib Dems and the Conservatives were likely to win, should “vote with their heads not their hearts”.