Election 2015: BBC debate 'worm' explained
The leaders of five of Westminster's opposition parties are due to appear in a live election debate on Thursday.
Labour leader Ed Miliband, UKIP's Nigel Farage, SNP leader Nicola Sturgeon, Leanne Wood of Plaid Cymru and the Greens' Natalie Bennett will take part.
The debate, hosted by David Dimbleby, will start at 20:00 BST and the BBC has gathered a group of 50 undecided voters to get their instant reaction to what is said.
Viewers will be able to see how they rate the leaders throughout the exchanges by watching 'the worm' as the BBC's Reeta Chakrabarti explains.
16 Apr 2015