Any Tory MP can throw his or her hat into the leadership ring, requiring just a proposerandseconder.
BBC: A cumbersome procedure
2.
Treasury spokesman Malcolm Bruce has the backing of three, while Simon Hughes, Don Foster, David Rendel and Jackie Ballard have just two MPs each to act as proposerandseconder.
BBC: News | UK Politics | Lib Dem contenders compete for MPs' support
3.
They must also find the backing of at least two members of the Liberal Democrat parliamentary party - one proposer, and one seconder.