Farage gets to enter the political establishment, while Clegg has a chance to reconnect with those voters who warmed to him in 2010.
Danny Alexander and Lynne Featherstone are both vulnerable to Labour challenges.
It will become harder for the PM to insist he can succeed when the europhile and the europhobe both declare he will fail.
The Tories could use a debate between the Lib Dem leader and his UKIP opposite to argue for the head-to-head contest they want between the two main leaders.
Local voters resent outside interference and Lib Dem activists will be encouraged to rush to their leader's defence.
The Deputy PM's warning that he would "absolutely insist" that a new coalition would not "break the bank" suggests that he may push Labour to back an Osborne-style deficit plan.
With the personal allowance already at £10,000, the lowest-paid five million workers will not benefit from further increases.
The Rennard shambles risks undermining the graduation into a serious party of government.
To allow the Liberal Democrats to swap sides without incurring any penalty would offend the essential order of our democracy.
Miliband and Clegg are ready to sign up to three debates over three weeks. They say Cameron is running scared.