Andy Burnham today set out his bid to ditch the UK's 'first past the post' voting system for general elections.The prime minister-in-waiting said he wanted Labour to make a commitment to electoral reform in the party's next manifesto.It came as the Makerfield MP, who is almost certain to succeed Keir Starmer in Downing Street, was quizzed about his stance on proportional representation.Mr Burnham said he was a 'strong supporter' of electoral reform as he insisted it would 'enable the change to a more collaborative politics'.It was among a number of questions that Mr Burnham answered on social media site Reddit, as he prepares to become PM as soon as 20 July.But the former Greater Manchester mayor was accused of 'hiding' from 'scrutiny' by opting for 'softball questions' on the internet.Tory leader Kemi Badenoch demanded Mr Burnham face 'a proper press conference', which he later acknowledged was a 'fair challenge'.During his 'Ask Me Anything' session on Reddit, in which he selected which questions he answered, Mr Burnham committed to keeping the state pension triple lock in place.In between questions about his favourite films and bands, Mr Burnham also said he would 'build' on Sir Keir's Brexit 'reset' and ruled out calling a snap general election. Andy Burnham was accused of opting for 'softball' questions on social media site Reddit, as he prepares to become PM as soon as 20 July Tory leader Kemi Badenoch contrasted her approach to media questions to that of Mr Burnham's this week, as she submitted her own question to him on RedditMr Burnham returned to Westminster after winning the Makerfield by-election on 18 June.He has since been coy about his plans for Government and exited a speech he gave in Manchester on Monday without taking questions from the media, leaving the country little clearer about details of his policy platform.Mrs Badenoch contrasted her approach to media questions to that of Mr Burnham's this week, as she submitted her own question to him on Reddit.'Whilst you're answering softball questions on Reddit, I've been in Yorkshire answering questions from the press,' she wrote.'You're going to be Prime Minister soon so it's time to start acting like one.'Come out from hiding, face a proper press conference and submit yourself to scrutiny and some tough questions. Are you up for it?'The Tory leader's question was among around two dozen that Mr Burnham chose to answer, writing in reply: 'Fair challenge, Kemi – but don't forget it's only two weeks since I faced questions from 74,000 members of the public in Makerfield!'Mr Burnham was also quizzed about whether he would abolish the triple lock on state pensions, to which he replied: 'I appreciate there's a lot of debate about this but it is important that the commitment in the manifesto stands.'Writing in response to a question about whether supported the introduction of proportional representation, Mr Burnham said: 'I am a strong supporter of electoral reform, partly because I believe it will enable the change to a more collaborative politics, and one that is less about point-scoring and more about problem-solving.'I will seek to persuade my own party of the need for a manifesto commitment to it in the next manifesto.'Labour's party conference voted to support moving towards a proportional representation voting system in 2022.But the party's 2024 manifesto instead focused its electoral and constitutional changes on extending voting to 16 and 17-year-olds and House of Lords reform.During the session, Mr Burnham ruled out calling a snap general election if he becomes PM.'No. As I said in my speech on Monday, I'm going to work to the 2024 manifesto,' he wrote.He also vowed to ensure the Government's recently-published Defence Investment Plan is 'fully funded'; said he would '100%' provide the same level of support to Ukraine; and said he would seek to negotiate return agreements with countries like Afghanistan for those who have had their asylum claims rejected.Mr Burnham pledged to 'build on' Sir Keir's efforts to forge closer ties with the EU when asked by a Reddit user if he would continue with the Government's attempts to reset the UK's relationship with Brussels, including whether he saw 'scope for negotiating a more ambitious trade agreement than the one we currently have?'He replied: 'Yes, I will build on the good work the Government has already done in this area.'Mr Burnham said his top four favourite films were Goodfellas, The Big Short, Brassed Off, and Pride.When asked about his current favourite music artist, he replied: 'I've been stuck in a Doves phase for quite a while…'