George Eaton makes the case:
As UK Polling Report's Anthony Wells notes, the Lib Dems are now in second place in 242 seats, up from 188 at the last election. And the party is now within 10 per cent of the winning party in 45 seats, up from 31 in 2005. By contrast, Labour is now in third place in 232 constituencies, up from 151 at the last election. There are large parts of the country, most notably Scotland and inner city London, where the Tories were pushed into third place in 1997 and have struggled to win ever since. Some in Labour must now fear that they face the same fate.
Clegg as PM? Maybe Cleggmania has yet to run its full course.