The nuclear option of attacking Clegg personally and portraying him as Cameron-lite was always open to Huhne, but I only expected him to deploy that option had it reached the point where he had nothing to lose. What I cannot understand is why he opted to deploy it at this stage, after a strong Question Time performance last week which would have persuaded many undecided party members to vote for him.
For what it's worth, my view is that they will now be less likely to do so. However its MPs might behave, the Liberal Democrat grassroots are emphatically not the nasty party, and its membership will take a dim view of anyone who so openly attacks a colleague.
Whichever of the two candidates ends up as leader, they are both major assets to the party, and for one of them to attack the other in that way diminishes that asset as well as dividing the party. In the words of one opposition commentator today, "anyone who was thinking of voting LibDem will have been profundly put off by the whole episode."
One person who knows this all too well is Gordon Brown. In 1994, he could have deployed the nuclear option against Tony Blair, portraying him as SDP Mark II (if only...!) and highlighting his policy flip-flops in much the same way Huhne did to Clegg.
I still believe Brown could have beaten Blair by employing such a strategy, but he knew that the party would have ended up so divided that victory would not have been worth the candle. I fear that this is now the fate awaiting Huhne should he go on to defy the odds and win.