Despite an often fractious relationship during their time in government, the two coalition parties, with a majority in the House of Commons, have pledged to maintain their partnership until the next general election, expected in 2015. The party leaders, Mr. Cameron for the Conservatives and Nick Clegg for the Liberal Democrats, have said that differences on a wide range of other policy issues will be subordinated until then to the parties’ common agreement on the need for harsh spending cuts to rein in a ballooning government deficit.

Still, political commentators said that Mr. Huhne’s resignation would have significant repercussions within the government and inside his own party. Mr. Huhne, a former financial journalist who made a multimillion-dollar fortune in the investment business before his full-time entry into politics, has been one of the most forceful figures in the government. He has been widely credited with pushing for Britain to adopt “greener” policies on climate change and to take a leading role in international efforts toward ambitious carbon-reduction targets.

But that has sat uneasily with many Conservatives, who have questioned some of the climate change science that has driven Mr. Huhne’s approach. They have also said that Britain, with a flagging economy and a debt that recently passed £1 trillion, or $1.6 trillion, for the first time, cannot afford the commitment Mr. Huhne has made that Britain will cut its carbon emissions by 50 percent by 2025.

An exchange of letters between Mr. Cameron and Mr. Huhne after the energy minister’s resignation was terse. Mr. Huhne said it had been “an honor to negotiate then serve in the first coalition government of modern times.” Mr. Cameron replied that Mr. Huhne had made “a very significant contribution to the government of which you can be justly proud,” and added, “I am sorry to see you leave the government under these circumstances and wish you well for the future.” He made no mention of a possible return to the government for Mr. Huhne if he is acquitted at trial.