A senior Conservative is being forced to fight a summer by-election after the contest in his constituency was postponed following the death of a rival candidate.

Electioneering in the Staffordshire South seat of Sir Patrick Cormack has ended after Jo Harrison, the Liberal Democrat hopeful, died after a short illness.

Under election law the poll is delayed if a candidate dies after the close of nominations.

The returning officer will ask parliament to convene a by-election within a month - with the seat lying vacant until the end of June.

Sir Patrick has a 7,000 majority, although he could face a tough fight following what some predict could be a third Labour landslide on May 5.

"I am obviously extremely distressed at the death of my Liberal Democrat opponent, and very sorry indeed that I am not going to be in a position to return to Westminster on May 11, but we will be doing everything possible to ensure we come back at the by-election," he said.

Labour candidate Penny Barber added: "It is a huge shock and a terrible shame. Our thoughts go out to her family and friends."