Wisconsin, which President Barack Obama won by 13 points in 2008, is looking like an increasingly close contest in 2012, according to a poll released Thursday afternoon by CNN/ORC International.

The poll shows Obama 4 points ahead of GOP presumptive presidential nominee Mitt Romney, 49 percent to 45 percent. Another poll, conducted Wednesday by Rasmussen, showed Romney edging ahead, 48 percent to 47 percent.

Both polls were conducted after the announcement of Rep. Paul Ryan (R-Wisc.) as Romney's running mate, but the CNN poll suggests that any bump from Ryan's announcement was modest, even within his home state. Polls from Marquette Law School and from Quinnipiac for the New York Times and CBS, done in early August, both showed Obama ahead by similar margins.

Romney's choice of VP was viewed positively by 51 percent of Wisconsin voters, while 30 percent said he made the wrong choice, according to Rasmussen.

HuffPost Pollster's chart, which is based on all publicly available polling, shows Obama maintaining a 4-point lead:

The CNN poll surveyed 920 registered voters by live telephone on Aug. 13 and 14, with a 3 percent margin of error. The Rasmussen poll surveyed 500 likely voters by automated phone on Aug. 15, with a 4.5 percent margin of error.

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  • Osama Bin Laden Killed -- "Tonight, Tonight"

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  • Debt Ceiling Deal -- "Gold On The Ceiling"

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  • Don't Ask Don't Tell -- "Don't Stop Believin'"

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  • Iraq War To End -- "Homeward Bound"

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  • Singing Al Green's "Let's Stay Together"

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  • Singing Robert Johnson's "Sweet Home Chicago"

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    <a href="http://www.huffingtonpost.com/2012/06/15/obama-immigration-order-deportation-dream-act_n_1599658.html " target="_hplink"><strong>(June 15, 2012) --</strong></a> The Obama administration addressed America's immigration issue, announcing that it will halt deportations and grant work permits to young individuals eligible for Dream-Act benefits. "They pledge allegiance to our flag," Obama said. "They are Americans in their hearts, in their minds, in every single way but one: on paper."(Photo by Alex Wong/Getty Images)

  • Health Care Reform -- "Beautiful Day"

    <a href="http://www.huffingtonpost.com/2012/06/28/supreme-court-health-care-decision_n_1585131.html" target="_hplink"><strong>(June 28, 2012) --</strong></a> After weeks of speculation that Obama's signature piece of legislation could be overturned, the Supreme Court ruled that the Affordable Care Act's individual mandate is constitutional. "It should be pretty clear that I didn't do this because it's good politics," <a href="http://www.huffingtonpost.com/2012/06/28/obama-health-care-ruling_n_1632953.html" target="_hplink">Obama said</a>. "I did it because it's good for the country." (Photo by Alex Wong/Getty Images)