Under our current voting system, voting for the candidate who represents the party you wan in government is not necessarily a smart way to vote. In some cases, choosing the party you want in government is throwing you vote away on a party that is very unlikely to win in your constituency. For instance in the constituency that I live in – Portsmouth South – anyone who votes Labour is pretty much throwing their vote away. The effective choices are between Liberal, or Conservative candidates.
With a transferable vote system (which of course we do not have), a Labour supporter (which isn’t me!) may well vote Labour as their first choice, and Liberal as their second choice to reduce the possibility that the Conservative candidate would win. Similarly, a Tory supporter in Scotland may choose Liberal as their second choice to reduce the chance of a Labour candidate winning.
Under our current system, it is probably better to choose between the two (or rarely three) leading candidates, picking the one that you least dislike the least. Whilst it may go against the grain to vote for somebody other than your preferred candidate, it does mean that your vote against the candidate you dislike the least is more effective.
Smart tactical voting is more complex than this of course – it involves checking the details of your constituency (you may also want to check the Voting Power details for your constituency, and the relevant Wikipedia article), and working out from the previous election results which two (or three if the third is within about 5% of the second placed candidate) and working out which one you would least dislike.
The Tories are warning that a vote for the Liberal party is voting to keep Gordon Brown in power – which is effectively saying that smart voting can accomplish something, but obviously slanted towards favouring voting Tory wherever you are. Whilst no party will encourage tactical voting, it can be for the benefit of whatever party you would prefer.
Vote tactically – it’s the smart thing to do!