Business minister, who recently returned from maternity leave, would replace Ed Davey.
To cement its identity in future coalitions, the party needs to own departments.
The Deputy PM's rejection of "austerity forever" is an important point of difference with the Tories.
On LBC's Call Clegg this morning, the deputy prime minister was challenged to show the Labour leader how eating a bacon sandwich is done.
The Lib Dem leader has avoided a palace coup but party activists are circling.
Lib Dem peer says his efforts to "expose and end cash-for-peerages in all parties, including our own" have failed.
Peer leaves the party and warns it is "heading for disaster" under Clegg.
"Appropriate steps" will be taken against the rebellious peer.
The party would perform no better under Cable, and Lib Dem voters and the party's 2010 supporters want him to stay.
The Lib Dem leader should seek a renewed mandate from his party.