Energy Secretary Chris Huhne resigned on Friday after being told he would be charged with perverting the course of justice over a 2003 speeding offence, in a huge blow to his Liberal Democrat party.
There was no immediate word on who would replace Huhne, the second prominent Liberal Democrat to quit the coalition government led by the larger Conservative party. His replacement will be another Lib Dem to maintain the coalition balance.
To avoid any distraction to either my official duties or my trial defence, I am standing down and resigning as energy and climate change secretary, Huhne said in a short statement less than an hour after the decision to charge him was made public.
His troubles stem from an allegation that after committing a speeding offence in 2003 in Essex, east of London, he asked his then wife Vicky Pryce to take the blame so that he would not lose his driving licence.
We have concluded that there is sufficient evidence to bring criminal charges against Mr Huhne and Ms Pryce for perverting the course of justice, Director of Public Prosecutions Keir Starmer said in a televised statement.
Starmer said the pair would appear for a preliminary hearing at Westminster Magistrates Court in central London on February 16.
Huhne says he is innocent and in his resignation letter to Prime Minister David Cameron he pledged to mount a robust defence.
Lib Dem insiders have said Employment Minister Ed Davey would be a likely choice to replace Huhne.
In his response to Huhne's letter, Cameron thanked him for his role in negotiating the coalition agreement and said he could be justly proud of his record in government.
You played a key role in securing the progress made at the Cancun and Durban summits (on climate change), and I pay tribute to the leadership you showed at both, Cameron wrote.
MORE MISERY FOR LIB DEMS
Cameron's warm words will be of little comfort to Huhne as his political career implodes with maximum embarrassment for his party.
The centre-left Liberal Democrats have had a bumpy ride since they formed the coalition with the right-wing Conservatives in May 2010. Their popularity has plummeted on a widespread perception that they abandoned several key campaign pledges.
Huhne's resignation follows that of David Laws, one of the party's leading lights, who quit over an expenses scandal in 2010 after just 17 days as Chief Secretary to the Treasury. He was replaced by Danny Alexander, another Lib Dem.
The Lib Dems are assured of just five senior cabinet posts under the coalition agreement.
Huhne is a wealthy former journalist who was a member of the European Parliament from 1999 to 2005. Elected to parliament in 2005, he stood for his party leadership the following year but lost to Nick Clegg, now deputy prime minister.
At last December's United Nations climate change talks in Durban, Huhne was credited with helping hammer out an international agreement on the cutting of greenhouse gas emissions.
(Additional reporting by Stephen Addison and Tim Castle; editing by Philippa Fletcher)