The rest of the state is a blend of blue collar strength in the mill and plant towns in the north, and deep pockets of social conservatives in rural areas, small towns and suburbs.
Republicans recaptured both houses of the Legislature in 2010 and now have the edge in Wisconsin's congressional delegation.
"We have been building momentum a long time," said Mary Buestrin, a Republican National Committeewoman from GOP-heavy Mequon, an upper-middle class Milwaukee suburb.
In the past three years, Wisconsin has begun bending away from more than a decade of Democratic-leaning statewide votes. Tea party favorite Ron Johnson turned back three-term Democratic U.S. Sen. Russ Feingold in 2010.
U.S. Rep. David Obey, a longtime leader on the House Appropriations Committee, saw his seat in jeopardy in 2010, and retired after 40 years representing northern Wisconsin.
Big-name Republicans, including longtime former Gov. Tommy Thompson and former U.S. Rep. Mark Neumann, are seeking the Senate nomination. Four-term Democrat Herb Kohl is retiring.
Adding to the attention, Wisconsin also boasts two prominent Obama antagonists: U.S. Rep. Paul Ryan, the House Budget Committee chairman, and Republican National Committee chairman Reince Priebus
Ryan received an ovation louder than Romney's when introducing the candidate Friday.
"We have a team of stars in Wisconsin the rest of the country is just learning about," said New Berlin Republican activist Pat Reinke, who attended the Romney rally. "Paul Ryan, Scott Walker, Ron Johnson, they are all gems."
Obama aims to make his race about the financial security of the middle class by painting his GOP rivals as beholden to interests of the wealthiest and of corporations. The Republicans say their goals of reining in government costs and regulations are about making sure companies can retain and expand payrolls in uncertain times.
Although George W. Bush lost Wisconsin in 2000 and 2004 by slim margins, the last Republican presidential candidate to carry the state was Ronald Reagan in his 1984 landslide re-election.
Even Democratic-leaning forces see a silver lining to the surge in confidence from the other side. The steady pace means voters will be deeply immersed in the issues, party lists of likely voters will be fresh and there will be lots of voter data to mine.
"They're getting engaged and it just carries over and builds," state AFL-CIO President Phil Neuenfeldt said. "We're building a movement here."
In the waning days of the late-starting Wisconsin primary campaign, Romney and Santorum have gotten into the act.
Santorum has praised Walker effusively for standing up to unions.
Besides winning Ryan's endorsement, Romney has attacked votes by Santorum, a former Pennsylvania senator, opposing legislation to block all states from requiring union membership as a condition of employment. Romney's campaign sponsored an automated telephone call praising Walker and condemning Santorum. The issue resonates with Wisconsin's especially anti-labor Republican electorate.
Romney's move could be a decisive one in Wisconsin, where he leads Santorum in polls. Santorum has lost Michigan, Ohio and Illinois to Romney, making Wisconsin the final chance for Santorum to make good on his argument his background from swing-state Pennsylvania makes him a good match for Obama.
But Wisconsin's unions remain strong and have the financial backing of their national affiliates, making Romney's attack on Santorum's support for private sector unions a potentially dangerous move for the general election.
"I think private sector union stuff is a good thing for Romney not to touch here," said GOP strategist Graul, a veteran of statewide and presidential campaigns in Wisconsin. "Even Gov. Walker hasn't said he's trying to push right-to-work."
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