The latest dispute could provide Cameron with another excuse to avoid taking part.
The ideological differences between the parties are greater than for decades. But their shared culture means few have noticed.
Backbenchers who were in despair last autumn are confident that their party has had the best start to the year.
The Mayor will not allow himself to be outflanked on national security in a future Conservative leadership contest.
Tactical voting, fewer wasted votes and lower turnout explain why the party can win more seats with the same number of votes.
The Conservatives' fixation with their past triumph is a mark of their present weakness.
Osborne's claim of a "blackhole" in Miliband's plans is forcing his party to shout louder about its commitment to continued austerity.
The PM is giving the false impression that most of the pain lies in the past.
George Osborne and his ministers once mocked the opposition for the goal they now boast of achieving.
The shadow chancellor remembers that it was fear of "Tory cuts" that handed Labour victory in 2001 and 2005, and denied the Conservatives a majority in 2010.