David Cameron's leadership of the Conservative Party seems, already, to have triggered a crisis in the Liberal Democrat Party.
Polls seem to suggest that while Cameron's Conservatives have a small lead over Blair's Labour Party, the expected succession of Gordon Brown as PM would lead to the Conservatives picking up votes at the net expense of the Lib Dems.
It seems to work like this: some people think Blair is really a conservative, and this is attractive to some people but not to others. With Blair off the scene, people who only vote Labour because of Blair will swing back to the Conservatives while people who refuse to vote Labour because of Blair - and currently support the LibDems - will return to the Labour fold.
This has led to senior LibDems asking the question, is it now time for us to change our leader? Combined with the lack-lustre leadership of Charles Kennedy and his frequently denied but now admitted drink problem, one senior colleague has already called him a "dead man walking".
But where now? The LibDems problem seems to be one of direction. They could follow the route outlined in the Orange Book - which advocates a return to the Liberal Party's Gladstonian roots - individual liberty and free market economics. Alternatively they could continue the current strategy of being a left-wing alternative to Labour.
Both strategies are problematic, because significant elements in the party oppose each route, and because it is not clear that either market position is - or will be by 2009 - available.
If Labour returns to its traditional values, there is little room for a party to its left. But a resurgent Conservative Party rarely leaves room for third parties (see election results of 1951, 1970 and 1979). David Cameron, in particular, is unlikely to cede any classical liberal ground.
The position is further complicated by the fact that a leadership election is not necessarily the best way to choose a strategy. It is not just a strategic choice but a choice of a leader who is willing, and able, to implement the strategy. How would a LibDem member vote if he believed that the Orange Book route was the wisest course, but felt that Simon Hughes was the most articulate and charismatic leader?
Furthermore, because Kennedy has called a leadership election, but intends to contest it himself, some potential candidates are ruling themselves out. That's how Margaret Thatcher became leader of the Conservative Party. She was prepared to challenge the incumbent leader when more senior colleagues presumed to have wider support were not.
If the LibDems want to take the left of Labour route, the choice is easy: they elect Simon Hughes, who came second last time and currently serves as Party President. If they want the Orange Book approach, Mark Oaten is probably the best candidate, but he has said he won't stand against Kennedy. If they want to postpone the decision for a few more years there is Deputy Leader, Menzies Campbell, but he too is not planning to fight Kennedy for the top job.
It's a mess, and there is no obvious way out.