just to expand on that, in the USA they vote for a head of state - that would be like British voters electing the queen rather than Blair. The US equivalent of Blair is the party leaders in the Congress. But what they sometimes do is elect someone from one party to be president and the other party to have the most seats in Congress. Or even more confusingly, one party to control the Senate and the other to control the House of Representatives. (At the moment, they're all Republicans; that could change after elections coming in November.) That's why congressmen wasted so much time and money trying to impeach Clinton: they were from the other party. This isn't necessarily a great model to follow.