Gordon Brown is to announce plans to look at a new system of electing MPs, as he seeks to regain the political initiative after a week of turmoil. He wants a debate on whether the vote system should change but will pledge a referendum on any move to do so. Ministers are thought to have discussed an alternative vote system to replace the current first-past-the-post method.

Mr Brown’s statement to MPs, expected at 1230 BST, comes as he seeks to reassert his authority following the departure of six cabinet ministers, disastrous election results and direct challenges to his leadership.