Some conservatives have targeted former Wisconsin Gov. Tommy Thompson for deficits and increasing the size of the states government and have used his failed run for the Republican presidential nomination in 2008 to gin up the same anti-establishment sentiment that has cost other candidates their races.
The campaign also points to state Republicans lining up behind Thompson's bid, including Attorney General J.B. Van Hollen.
Neumann came to Congress during the Republican revolution of 1995 and served two terms. He left the House to challenge former Sen. Russ Feingold (D) in 1998 and narrowly lost. He lost a GOP gubernatorial primary last year.
Wisconsin Democratic Party spokesman Graeme Zielinski labeled Neumann "a perennial loser." But the attempts helped him build up his name identification.
In addition to his Club for Growth backing, Neumann was endorsed last week by conservative GOP Sens. Rand Paul (Ky.) and Tom Coburn (Okla.).
One GOP strategist in the state suggested endorsements from Senators with high national profiles won't matter, and it's still to be determined whether Sen. Jim DeMint's Senate Conservatives Fund, which caused some mischief during the 2010 primaries, will get involved in this race. National tea party groups could join the Club for Growth and spend heavily against Thompson if they decide to weigh in, but Thompson seems to have locked in strong local support.
"He's got a lot of old-guard Republicans, people who are involved in politics, have been involved in politics, that are in government affairs or loyal backers in communities that are doing some grass-roots outreach on their own to build message and to support his candidacy," said outgoing Jefferson County Republican Party Chairman Matt Banaszynski, who is unaligned in the race. "It appears that he's got this pretty big presence."
Neumann and Fitzgerald have ties to Gov. Scott Walker (R).
Neumann lost a gubernatorial primary to Walker after a fight operatives described as "pretty nasty." Fitzgerald has worked closely with Walker as state Speaker.
Walker's anti-collective bargaining efforts have rocketed him to the national stage as interest groups prepare for a Democratic-led recall effort next year.
The potential recall is consuming most of the political oxygen in the state. As Democrats and unions were preparing to launch the effort last week, Walker paid to air an ad during the Green Bay Packers' Monday Night Football game. The ad featured a school board member praising the governor for giving the board "options" to manage the budget. "Wisconsin's best days are yet to come," Walker says in the ad.
If the anti-Walker movement obtains the required signatures necessary to move forward with a recall, it is estimated that election will take place in May or June, depending on legal maneuvering.
In addition to that activity and the Senate battle, Wisconsin will be a battleground in the presidential contest. So Badger State voters should expect to be inundated with political activity through Nov. 6.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.