A head to head comparison of the 2008 Wisconsin General Election gives us an idea of the break down of the voters.    

Barack Obama received 1,677,211 (56%) votes, beating John McCain who gained 1,262,393 (42%) by 414,818 votes in Wisconsin.

Barack Obama won 59 counties whereas John McCain won 13 counties in the total of the 72 counties in the State of Wisconsin.

Presidential General Elections

During the 2008 General elections, over 131M total number of votes were cast. Barack Obama got 69,448,278 (69.4 Million) over John McCain's 61,739,059 (61.7 Million). He won the popular vote by 7,709,219 (7.7 Million). His victory in the State of Wisconsin (with 1,677,211 votes) represents 2.4% of his popular vote victory. The remaining 49 states contributed to the remaining 97.6% popular votes victory.

Top 15 Counties in Primary Elections vs General Elections

All Candidates (General Elections)

These 15 counties play an important role in these Primary elections. If a candidate, can get a sizable majority in the largest counties (Milwaukee, Dane, Waukesha, Brown), it becomes very difficult to win majorities in the smaller counties without voter outreach and increased voter participation in them.

Top 15 Counties Comparison in Primary Elections vs General Elections

General Elections
Barack Obama

General Elections
John McCain

Milwaukee, Dane, and Brown, three of the larger counties, voted in favor of Barack Obama giving him a 314k vote advantage. Waukesha, another larger county, voted in favor of John McCain giving him a 59k vote advantage. However, Barack Obama's steady marginal wins in the less popular counties (like Kenosha, La Crosse, Eau Claire and more) were enough to maintain that lead over John McCain, making him gain an upper hand in the State of Wisconsin.

Related References: 2016 Wisconsin Primary Election Story, 2016 Wisconsin General Election Story, 2020 Wisconsin Primary Election Story, 2020 Wisconsin General Election Story, 2012 Wisconsin General Election Story