"... move the needle of public opinion ..."

"Sandy may move the needle of public opinion a little further. Should he win next Tuesday,Mitt Romney, who cannot admit to even believing that humans cause climate change, is unlikely to do anything about the problem. If Obama is re-elected, he will have no choice but to lavish a great deal of political capital on this intractable subject. But isn't that what a second term is for?"
More: Adapt or Die - By James Traub | Foreign Policy

Does move the needle of public opinion mean to prepare public opinion for/to such discussion or to make people think seriously?

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