GREEN BAY, WIS. - The presidential race came barreling into an ice rink last week in a sprawling suburban office park, where GOP vice presidential candidate Paul Ryan, Wisconsin's native son, excited the crowd with shout-outs to the Green Bay Packers and references to a local brand of jalapeño jam.
No Republican has won a presidential race in this state since 1984, long before some of the college students cheering for Ryan were born.
But this year, with Wisconsin joining Ohio and Iowa as tossup states, there's a "Big 10" aspect to the 2012 election, which could well be decided in the industrial Midwest heartland, always a pivotal region of the nation.
Ryan, leading a town hall forum of 1,500 people Wednesday, was on his third stop in Wisconsin since signing on as Mitt Romney's running mate last month, and on Saturday was back in the state again, visiting Madison. Vice President Joe Biden campaigned in Eau Claire on Thursday.
Romney has been here twice since June, while Biden and First Lady Michele Obama have made three stops between them. Next weekend will be President Obama's turn, with a fundraiser and roundtable discussion scheduled in Milwaukee.
The money is pouring in, too. The Romney campaign snagged an estimated $360,000 television ad buy. The Obama campaign has followed suit.
Wisconsin voted overwhelmingly for Obama last time, but it has become a political powder keg since then, with regular clashes between a staunchly conservative governor and enraged union workers. The Great Recession crippled job growth here and has left many undecided about who can best turn the nation around.
Concordia College student Tom Reddington, who came to see Ryan, is among those hoping Wisconsin will break its 24-year streak of voting to send Democrats to the White House. "I feel like it's going to be very close," he said.
Strategists in both campaigns say the reason they are devoting so much time and money in the nation's heartland -- particularly Wisconsin, Iowa and Ohio -- is the region's legacy of pragmatic voting and its shifting allegiances.
A quick glance at any electoral map of the United States shows a big splotch of predictably Republican -- red -- states in the South and Mountain West, book-ended by columns of mostly Democratic -- blue -- states on the Northeast and West coasts.
Between them lies the agricultural and industrial Midwest, where the road to victory goes through a checkerboard of states that changes colors from one election to another, often tipping the scale in tight presidential races. A blend of big cities, suburbs and farm country, the region presents a diverse political kaleidoscope.
"If you look back historically, the Midwest tends to be one of the best bellwethers," said Gallup researcher Jeffrey Jones. "It mirrors the nation as a whole, whereas other regions shade more in one direction."
Wisconsin and Iowa went to Obama in 2008, but both are within striking distance for Romney in 2012. The same is true for Ohio, epicenter of the 2012 Midwest battleground and a must-win state for Romney that has unfailingly picked the winner in modern election history.
Another sign of the region's importance was seen in the short list of Romney's VP selections, which included Ohio U.S. Sen. Rob Portman and former Minnesota Gov. Tim Pawlenty.
Even in Minnesota, which hasn't voted for a Republican presidential candidate since 1972, voters have shown an independent streak in statewide elections that leaves political operatives room to maneuver.
"They tend to think more independently and they're more practical about their politics," said Iowa GOP strategist David Kochel, a consultant to the Romney campaign. "They're focused on performance, not ideology."
In a region hard-hit by the recession, a key factor will be whether voters believe jobs are coming back fast enough under Obama. That's a performance measure that has Republicans talking about plant closings in the industrial heartland and Democrats talking about the auto bailout and slowly falling unemployment rates.
"Across the board throughout the Midwest is the understanding that you need to be pragmatic and forthright about what you want to do to make sure that we're improving every day," said Ben Finkenbinder, a spokesman for the Obama campaign in the Midwest.
"The economy is the Number One issue everywhere. But within the Midwest, what you see ... is what the shift in jobs could have been if the president hadn't fought for the auto industry."
The Midwest, birthplace of the U.S. labor movement, also has been a battleground over collective bargaining, with Wisconsin and Ohio hosting major battles over the union rights of public workers. Wisconsin Gov. Scott Walker, who survived a recall election over his move to weaken worker rights for government employees, gave Republicans hope of winning the state's 10 electoral votes this year.
Minnesota, with an unemployment rate below the national average, appears to be tilting toward Obama, with a recent poll showing a double-digit advantage over Romney. But the state shares similar demographic characteristics with Iowa and Wisconsin, and, to a lesser extent, Ohio.
Complicating Romney's task of emphasizing the downside of the Obama economy is the fact that the three most likely Midwestern swing states have Republican governors who have little reason to accentuate the negatives.
Still, while Wisconsin has not voted for a Republican since 1984, it was among the closest contests in the nation in two of the past three presidential elections. And this year, with Ryan on the GOP ticket, Democrats are vowing not to take anything for granted.
"In a lot of respects, the battlefield has expanded, not contracted, and Wisconsin is one of the states that's now in play," said Rich Chrismer, a Romney campaign adviser for the Midwest.
But a Monmouth College Midwest Matters poll this year of registered voters in eight Midwestern states -- including Minnesota -- found Midwesterners as a whole remain largely pro-union, if somewhat less sympathetic toward public employee unions. By a 2-to-1 margin, they also believe the nation is headed on the wrong track, but better than a year ago.
That's a mixed message that has helped define the contours of the election contest in the nation's pivotal midsection. Said Robin Johnson, the author of the Monmouth survey: "This election is going to be decided in the Midwest."
Kevin Diaz is a correspondent in the Star Tribune Washington Bureau.