Polls have opened in by-elections in London and County Durham.
Voters in Ealing Southall in west London and Sedgefield will today select their new MP.
Labour are expected to hold on to Tony Blair's former seat of Sedgefield but the Liberal Democrats have made strong gains in Ealing Southall.
Labour candidate Phil Wilson is widely expected to be elected in Sedgefield today.
Mr Blair stood down as an MP when he resigned as prime minister, triggering a by-election. He said he wanted to concentrate on his new role as Middle East peace envoy on behalf of the Quartet.
The former prime minister held the safe Labour seat since it was created in 1983 and won a majority of more than 18,000 at the last election.
Piara Khabra's death in June triggered an election in Ealing Southall. The Labour MP had held the seat since 1992 and won a majority of 11,440 in the last election.
The Liberal Democrats last night claimed their candidate Nigel Bakhai was neck and neck with Labour challenger Virendra Kumar Sharma.
Making his seventh visit to the constituency, Liberal Democrat leader Menzies Campbell said: "In the last few weeks momentum has been building behind Nigel Bakhai as people back the local choice.
"As we enter the final stretch, it's neck and neck between the lib Dems and Labour".
Sir Ming said the Tory campaign was in "freefall", as senior Conservatives privately admit they are unlikely to win the predominantly Asian constituency.
The campaign in Ealing Southall has threatened to descend into farce, with senior council members switching allegiance and independent candidates deciding to campaign for their rivals.
The Conservatives were also embarrassed when candidate Tony Lit was photographed smiling alongside Mr Blair at a Labour fundraiser.
Polls close at 10pm and pleasant weather could lead to a high turnout.
Candidates for Sedgefield:
- Stephen Gash - English Democrats - "Putting England First"
- Paul Gittins - Independent
- Tim Grainger - Christian Party "Proclaiming Christ's Lordship"
- Chris Haine - Green Party
- Alan 'Howling Laud' Hope - The Official Monster Raving Loony Party
- Toby Horton - UK Independence Party
- Graham Robb - Conservative Party
- Norman Scarth - Anti-Crime Party
- Andrew Spence - British National Party
- Greg Stone - Liberal Democrat
- Phil Wilson - Labour Party
Candidates for Ealing Southall:
- Nigel Bakhai - Liberal Democrats
John Sydney Cartwright - The Official Monster Raving Loony Party
Sati Chaggar - English Democrats - 'Putting England First!'
Salvinder Singh Dhillon - Respect - Peace, Justice, Equality
Sarah Janet Edwards - Green Party
Kuldeep Singh Grewal - Independent
Tony Lit - David Cameron's Conservatives
Yakub Masih - Christian Party 'Proclaiming Christ's Lordship'
Jasdev Singh Rai - Independent
KT Rajan - UK Independence Party
Virendra Kumar Sharma - The Labour Party Candidate
Gulbash Singh - Independent