Iain Duncan Smith: I'm no quitter
The polls have closed in a vote of confidence that will decide whether Iain Duncan Smith remains Tory leader.
Votes are now being counted after the secret ballot closed at 1830 GMT, with the result expected just before 1900 GMT.
Mr Duncan Smith needs a straight majority of the votes cast to keep his post.
Ahead of the ballot boxes opening at 1530 GMT the Tory leader urged his party's backbench MPs to back him, in what was described as a "blazingly honest and very direct" speech.
But if he fails to win support from a majority of those who vote he loses his job and is ruled out of the ensuing leadership contest.
Arriving at the House of Commons committee room where the MPs were gathered before voting got underway, the Tory leader smiled and said: "It's like a sort of gladiatorial thing, isn't it?"
He then pleaded with his parliamentary colleagues to bring to a close a decade of divisions and endorse his leadership, warning there was no "white knight" to come charging to the rescue.
He said recent weeks had been "a vision of hell" for the party.
The ballot was open to all 165 Tory MPs.
Mr Duncan Smith has already said if he loses the confidence vote he will stay on as a caretaker leader until his successor is elected.
He also pledged that if ousted he would not carp from the sidelines.
His speech to backbenchers lasted around half-an-hour, during which he received two table-thumping and foot stamping ovations.
First to arrive to vote was Ann Winterton, sacked as a front bencher by Mr Duncan Smith. She was followed by former chancellor Ken Clarke, Desmond Swayne and John Gummer who all left without commenting.
The Tory leader arrived shortly after, followed by various members of his shadow cabinet.
Earlier Mr Duncan Smith received cheers as he faced Tony Blair for prime minister's questions, challenging him about rising crime rates and the proposed EU constitution.
The Tory leader had been in bullish mood during an early round of media appearances, insisting he welcomed the opportunity to clear the air and saying he was "not a quitter".
TIMETABLE FOR WEDNESDAY
1200 GMT Prime minister's question time
1400 Deadline for proxy votes
1430 Iain Duncan Smith addressed special meeting of Tory backbenchers who make up the 1922 Committee
1530 Confidence vote opened
1830 Vote closes
1900 Result is announced
He said the choice was between him taking the party to the next election as "a unified force", or the Conservatives plunging themselves into "a war of words" with a leadership contest that would lose them "the opportunity to beat the government at their most critical and vulnerable time".
Mr Duncan Smith said he had ignored the continued vilification of his character in the media because he believed what he was doing was right.
"The only reason I am doing this is because I genuinely... believe passionately in this country and I believe the British people are the most decent, tolerant and determined I have ever met and they are worth fighting for and I am going to fight for them, not for myself."
'Courage and dignity'
The vote comes after Mr Duncan Smith challenged plotters to get in line or submit the 25 names they needed to trigger a ballot.
It emerged shortly after lunchtime on Tuesday that enough letters had been sent to the chairman of the Tory backbenchers' 1922 committee, Sir Michael Spicer, to force the contest.
Tory MPs who are unable to attend Wednesday's ballot were allowed to make their decision "by proxy" vote via fax, e-mail or letter, provided these arrived before 1400 GMT.
On Tuesday, four members of his shadow cabinet - Michael Ancram, Michael Howard, Oliver Letwin, Theresa May and later, David Davis - issued a statement of support for their leader.
Tory MPs Derek Conway, Crispin Blunt, Francis Maude, John Greenway, Sir Patrick Cormack and David Curry were the MPs to go public with their demands for a confidence vote.