Chris Huhne pleaded guilty to perverting the course of justice today, in a move with catastrophic repercussions for the Liberal Democrats and him personally.
The former climate change secretary entered the plea alongside his ex-wife Vicky Price at London's Southwark crown court this morning, shortly before resigning as an MP and triggering a by-election in Eastleigh.
"I have pleaded guilty today. I am unable to say more while there is an outstanding trial," he told reporters outside the court.
"But having taken responsibility for something that happened ten years ago the only proper course of action for me is to resign my Eastleigh seat in parliament which I will do very shortly. And that's all I'm able to say today."
The pair were charged over allegations Huhne persuaded Pryce to take his penalty points after he was caught by a speed camera between Stansted airport and London in 2003.
The allegations of wrongdoing were not made public until 2011, when Huhne's marriage ended following an affair with his press agent, Carina Trimingham.
Perverting the course of justice can result in a jail sentence of between four and 36 months, but on average sentences are around the ten month mark.
Any sentence over 12 months means Huhne must resign by law.
Justice Sweeney told him: "I will deal with your sentence on a date to be notified.
"As Mr Kelsey-Fry [Huhne's barrister] has foreshadowed, you should have no illusions whatsoever as to the sort of sentence that you are likely to receive."
Downing Street refused to comment on the developments, with the prime minister's spokesman saying: "Issues around this are a matter for Mr Huhne."
The Lib Dem majority in Eastleigh is 3,864, but with the coalition seen as increasingly toxic and Huhne's court case top of voters' minds, the party is likely to face a bloodbath in the Hampshire seat.
The Conservatives, who won 21,102 votes in 2010, covertly ramped up their campaign in the seat recently, but there could also be a serious threat from Ukip.
Leader Nigel Farage could well be tempted to make a run for the seat, with the euroseptic party relying on their stronger showing between general elections to aim for a major electoral upset.
The party secured 1,933 votes in Eastleigh in 2010. A Ukip spokesperson confirmed Farage was considering his options.
If the Lib Dems lose Eastleigh, it will mark the end of their 'golden triangle' in the south, together with Winchester and Romsey.
The triangle was a sign of the party's progress in southern, typically Tory seats, but both other seats went to the Tories in 2010.
Bookmakers William Hill make Tories the favourite to take Eastleigh off the Lib Dems with odds of 1/2. The Liberal Democrats are on 6/4 LD and Ukip 33/1.
The guilty plea also raises questions about Nick Clegg's judgement.
The two men were never seen as close, after a hard fought leadership contest saw Huhne's camp dub his opponent 'Calamity Clegg'.
But the party leader came to value his colleague in government as one of the few Lib Dems ready to stand up to Tories around the Cabinet table – particularly during the AV referendum campaign.
When Huhne stepped down from Cabinet, Clegg went out of his way to prepare the ground for a return.
"I have made it clear to him I would like to see him back in government in a key position," he said.
Speaking after the news today, Clegg said: "This is obviously an extremely serious matter and it's essential that the legal process is now allowed to run its course.
"I'm shocked and saddened by what's happened, but I believe that Chris Huhne has taken the right decision in resigning as an MP."
Huhne had been 2/1 favourite to take over as Lib Dem leader when Clegg stepped down, but he has now been replaced by Tim Farron on the same odds.
Vince Cable is on 5/2, Ed Davey on 7/1 and Norman Lamb on 12/1.
Huhne was granted unconditional bail.
The case against Pryce, Chris Huhne's was adjourned until 10)) GMT tomorrow. She was also granted unconditional bail.