Politicians often have to present to the public the notion that they support a particular set of ideas, not because they believe in them, but because the mentioned ideas are popular and likely to win votes. In the UK (at least) political parties also employ 'whips' who keep their members in check, meaning that unless a MP wants to be kicked out of their party they have to be seen to support (in public and voting) most of what their wider party supports regardless of their own beliefs.