There we go again:

You'll pledge £X billion to the NHS/education/services/blah *if* you win the election?  How dare you blackmail me, sir.  Basic services are not a carrot to be dangled come election time.  Wind your neck in and make sure it gets done regardless - not because you won or lost your glorified popularity contest, but because it's the right thing to do for the country.

That's your job and you should be grateful we gave it to you.  Not the other way around.