British voters don't vote for prime minister directly in England. Blair's not on the ballot except in his own district. The winning party in parliament selects its leader.
It's also been stated that stay-at-home non-voters will have an important impact as there will be so many of them.
Labour adherents are conflicted because they oppose the Iraq war, so rather than vote against their party, they'll sit tight.
Some other factors are causing voter apathy, too much detail to go into here.
About the only thing exiting the Tories this election is immigration. This may play a bigger role in this election than is thought. People don't want to talk about this subject openly or in pre-election polls. But the factor is there.....and who knows what role it will play.
Carry on.
Leni