Three weeks ago, Barack Obama had a narrow three-point lead in Wisconsin over Mitt Romney, 49/46.  In a poll taken yesterday of likely voters, Rasmussen notes that the race has shifted subtly.  Now Romney has the edge in a virtual tie over Obama, 48/47:

The presidential race in Wisconsin is a little tighter this month following Mitt Romney’s selection of hometown Congressman Paul Ryan as his running mate.

The latest Rasmussen Reports statewide telephone survey of Likely Voters shows Romney with 48% support to President Obama’s 47%. Three percent (3%) prefer some other candidate, and two percent (2%) are undecided. (To see survey question wording, click here.)

In late July, it was Obama 49%, Romney 46%.  This is the Republican’s largest level of support yet in the Badger State. Prior to this survey, the president has earned 45% to 52% of the vote, while Romney has picked up 41% to 46% of the vote.

Don’t get too excited over the results, at least not yet.  The shift here is within the poll’s margin of error.  It’s still better than the non-shift in yesterday’s Rasmussen poll of Florida, which still shows Romney edging Obama within the MoE and both candidates dropping.

Still, this result in Wisconsin seems to show that native son Paul Ryan will have a positive impact on Romney’s chances to be the first Republican to win Wisconsin since Ronald Reagan in 1984’s 49-state landslide.  That threatens to put pressure on Obama in Iowa and even Minnesota, although my state’s ability to go red has been a perpetual pipe dream since 1972.  It might force Obama to spend resources here that would have normally gone into Iowa and Missouri, though, two states that Ryan can definitely help Romney win.

The internals look pretty good for Romney in Wisconsin.  His three-point edge comes entirely from independents (46/43), while party loyalty is all but complete (only 1% of Republicans and 2% of Democrats switching).  Romney wins double-digit leads and majorities in the two older age demographics, but loses the under-40 demo by 19 points.  That’s hardly unexpected, and it might be better than Republicans would expect.

On favorability, Romney has even better news.  He’s +10 overall at 54/44, and he’s even a net positive among women (51/48) and even among the under-40 demo at 49/49.  Ryan’s favorability is even higher at 57/36, 52/40 among women and 46/42 among younger voters.  Among independents, Ryan gets a 61/31 +30 in favorability — a big boost, as Romney is only a +7 at 53/46.  Obama’s ObamaCare scares more voters than Ryan’s proposed changes to Medicare (48/42), with a +14 among independents in favor of Ryan (46/32), but a -7 among women (43/50).

The key question is whether Ryan on the ticket makes Wisconsin voters more likely to vote for Romney; overall, it’s a +15 at 46/31.  Among Republicans and Democrats, this probably measures enthusiasm more than an actual game-changer, since party loyalty is all but complete already.  On that basis, Romney gets an edge, since it helps with 85% of Republicans, while hurting with only 65% of Democrats.  Among independents, though, the gap is a +21, 49/28.  This could be a very big deal, especially with the advantages of Republican organization over the past year in GOTV efforts for the recall elections.