"Madison, these are the front lines in the battle for the future of our country," said Sarah Palin.

"This is where the line has been drawn in the sand, and I am proud to stand with you today in solidarity.... The 2012 election begins here."

The NYT highlights that quote and says:

... Ms. Palin’s appearance offered one early hint at Wisconsin’s rising significance in the presidential race ahead. The place has long been a battleground, politically divided, but what seems clear here now is that voters are especially energized, and that offers tantalizing prospects — on both sides.