(CBS News) In the wake of Mitt Romney's decision to tap Janesville, Wis., native Rep. Paul Ryan as his running mate, President Obama's longtime lead over Mitt Romney in the Badger State has evaporated: The president's six-point advantage has shrunk to just two points - within the margin of error - according to the latest Quinnipiac/CBS News/New York Times poll. Another survey from Marquette Law School released Wednesday showed the president with a three point lead, also within the margin of error, and two other polls this week also showed a tight race. The Marquette poll had Mr. Obama leading by 12 points in May.
Congratulations, Wisconsinites: You're officially living in a swing state.
Wisconsin hasn't backed a Republican for president since Ronald Reagan's reelection in 1984, and Mr. Obama won the state by a comfortable 14 points in 2008. But the state has shown a willingness to support Republicans: In 2010, voters sent Ron Johnson to the Senate and chose Scott Walker as governor. The state's Republican Senate candidate, Tommy Thompson, served as governor from 1987 and 2001. And while Democrat Al Gore won the state over George W. Bush in 2000, it was by the slimmest of margins: Just .22 percentage points. Same result in 2004: John Kerry eked out a win over Mr. Bush by .38 percent.
The new Quinnipiac/CBS News/New York Times poll suggested that a positive perception of Ryan is responsible at least to some degree for Romney's polling bump. "It's had some home-team effect, essentially," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute. While the impact of the Ryan selection does not appear to be overwhelming - 31 percent of likely voters say it makes them more likely to back the GOP ticket, while 22 percent say it makes them less likely to do so - it could be enough to put Wisconsin's 10 electoral votes into the Republican column.
The fact that Republicans tapped Thompson as their Senate nominee might, at first glance, suggests the conservative-courting Romney/Ryan ticket might struggle to win over the state's Republicans. Thompson has a reputation as a relatively moderate Republican in an age when the GOP has shifted to the right and taken its presidential ticket with it.
But Thompson's primary victory is, to some extent, less than it appears. He was able to win only because the support of conservatives was split between other candidates. Thompson himself only won about a third of the vote.
And keep in mind that the state's governor is by no means a moderate. Walker, who survived a recall election earlier this year, is a staunch conservative whose successful effort to curtail public employee unions' collective bargaining rights made him a figure of scorn on the left. The bill galvanized unions and helped transform Wisconsin into a deeply-polarized political battlefield.
Indeed, the defining feature of Wisconsin politics now may well be just how far apart the two sides have grown. Consider the Senate race: Thompson only squeaked through thanks to a split vote, and his Democratic opponent, Tammy Baldwin, is an unapologetic liberal. An openly gay champion of progressive causes from the Madison area, Baldwin describes Ryan as backing "harmful" policies that would "end Medicare as we know it."
What all this means for the presidential race is not yet clear. But the polarization of the electorate suggests that the election may come down to which side is best able to turn out its base - and on that front, the Ryan pick could be crucial, since it has helped unify a state GOP that had splintered during the contentious Senate primary process. On the flip side, Democrats built a strong organization during their failed effort to recall Walker that they have put back into motion for the November election. One concern for Democrats: In the Quinnipiac/CBS News/New York Times poll, Republicans are substantially more enthusiastic about voting this year compared to past years than Democrats. And enthusiasm has increased in the wake of the Ryan pick.
The top issue in Wisconsin, as in other states, is the economy. On that front Romney has the edge: In the new poll, he has a six-point advantage over the president on the question of who would do a better job handling the economy. But while Ryan's hometown status will provide a boost, his proposal to transform Medicare into a premium support/voucher system could hurt: Just 32 percent of the state's voters support such a transformation. And Mr. Obama has a six-point edge over Romney when it comes to how favorably the candidates are viewed in the state.