UKIP leader Nigel Farage has decided not to stand in the Newark by-election.
Mr Farage told the BBC that his decision was based on the timing of the announcement. He said he wanted to concentrate on a record-breaking result in the European elections in a couple of weeks' time.
"If I said yes (to standing in the Newark by-election) all the attention would be focused on me - am I going to win, am I not going to win," he said.
The by-election was prompted by the decision of former Tory MP Patrick Mercer to stand down after a parliamentary inquiry into cash for questions.