Energy Secretary Chris Huhne faces his moment of truth today when prosecutors reveal whether he will face charges for allegedly dodging a speeding penalty.
The announcement, which follows an eight-month police investigation, is due to be made in a dramatic televised statement this morning by the director of public prosecutions, Keir Starmer.
Any decision to proceed with the case is expected to spell the end of the Liberal Democrat’s Cabinet career – although he has repeatedly refused to confirm he would quit if charged.
His ex-wife, economist Vicky Pryce, is also set to learn whether she will face charges. The potential offence could be perverting the course of justice.
The alleged incident dates back nearly a decade, but only emerged after Mr Huhne admitted an affair with PR adviser Carina Trimingham in 2010 and ended his marriage.
It is alleged Mr Huhne had been caught speeding in Essex while an MEP in 2003. However, he is said to have escaped a driving ban by persuading Ms Pryce to accept the penalty points on his behalf.
Essex Police launched a formal probe in May, led by a detective chief superintendent, and the ex-ex-couple have been interviewed by officers twice.
Mr Huhne has repeatedly denied any wrongdoing, and both Lib Dem and Tory colleagues expressed support for his remaining in post during the investigation.
The CPS decision was delayed by a court battle to obtain key emails, finally handed over at the end of last month.
Mr Starmer will make the announcement live to camera at the CPS headquarters at 10am today, but will not take questions.
It is understood Mr Huhne will be told of the decision shortly before it is made public.
There has been fevered speculation at Westminster about the ramifications if the senior Lib Dem is charged.
Deputy Prime Minister Nick Clegg has warned that it would be a “very serious issue”, and insisted that the coalition was determined to uphold the “highest standards of probity” among Ministers. The Cabinet Secretary is also reported to have made clear Mr Huhne would have to resign in those circumstances.
Under the coalition agreement, the Lib Dems are guaranteed a proportion of Cabinet posts – with foreign Minister Jeremy Browne and business Minister Ed Davey regarded as favourites for promotion.
However, many believe David Cameron would use the departure to stage a wider reshuffle.
Downing Street said the Prime Minister had not been informed of the CPS decision, and did not expect to find out until after Mr Huhne and Ms Pryce.
A spokesman for Number 10 said the premier continued to have full confidence in the Energy Secretary and did not believe that the furore over the speeding allegations was getting in the way of the Government’s work.