The one flaw with tactical voting

And the reason Brown may be holding back from echoing Balls, Hain et al.

Mehdi Hasan's interview with Ed Balls continues to set the agenda in Westminster this afternoon, with mixed reports as to whether the Prime Minister backs Balls in joining Peter Hain, Douglas Alexander, Andrew Adonis and others in endorsing tactical voting in marginal seats to keep out the Tories.

The Guardian is reporting that Brown has indeed backed the call, while other outlets including Sky News are claiming that Brown is simply saying, "Vote Labour", which appears to be his latest message.

Earlier, I reported that some are saying Brown will disassociate himself from the plea, because if he made it, that would enhance the Tories' ability to say "Vote Clegg, get Brown".

But there may be another important reason why there are slightly mixed messages on this: the question of vote share, as well as seat count, is suddenly, as has been pointed out elsewhere, a factor in this election, a factor normally buried by the now popularly discredited first-past-the-post system.

Nick Clegg, for example, has suggested that he will not let Brown "squat" in Downing Street if Labour comes third in its share of the vote. For that reason, some in Labour -- including Alexander, who is reportedly worried by calls for Labour people to vote Lib Dem in marginals where the Liberals can beat the Tories -- are acutely aware that tactical voting could spell trouble.