After Chris Huhne's resignation a by-election will be held in his constituency of Eastleigh.
A source close to Labour leader Ed Miliband signalled the party's determination to fight for the seat:
It is understood that Eastleigh is 258th on Labour's target list.
The Liberal Democrat leader of Eastleigh Borough Council, Keith House, he was "very sad" about Huhne's resignation, saying he had been a "hard-working MP".
The Tory candidate is likely to be business consultant Maria Hutchings, 51, who famously assailed Tony Blair over care and education for her autistic son during the 2005 general election campaign.
A local party source said: