Do people think Murdoch has that much power? Or is it just illusory. Sure he has a loud megaphone to shout his opinions but I would suggest rather than lead opinions he follows them. By reflecting his readerships views he ensures he isn't at odds with them rather than trying to direct their views for his own, as yet unidentified purposes.
He supported New Labour when it became clear that their time was due and dumped them when it was clear they were done I don't think this changed opinion merely reflected it. Papers that fail to reflect their readers biases suffer, the Daily telegraph has lost circulation at the time it has set it's editorial slant at odds with its readership. The Sun is just avoiding this surely?
I think that's largely true, but what the papers write can also have an influence on the way people vote e.g. that photo of Ed Milliband eating a bacon sandwich certainly increased the mockery of him. To what extent this caused him to lose the election is debatable though.
I also get a sense in this campaign that senior politicians are starting to understand that they do not lead the British people - they can only represent them.