As voters go to the polls in six states today, super PACs and other outside groups are playing an outsize role in some of the high profile contests, as incumbent members of Congress square off against other incumbents due to redistricting, special interests duke it out in one district, and Democrats try to avoid being beaten out by an indepedent for the fall ballot. Here's a rundown of some of the spending:

Sherman v. Berman

Thanks to redistricting, one of the most high profile contests pits two House Democrats against each other in California's San Fernando Valley, where Brad Sherman takes on Howard Berman. So far, the outside money has only helped Berman, with a super PAC called Committee to Elect an Effective Valley Congressman spending about $550,000 on ads and mailings backing Berman. The money has only added to his financial advantage, with his campaign spending $2.7 million since January, about $1 million more than Sherman's.

Radio executive Marc Nathanson, who poured $100,000 into the super PAC through his company, formed the Committee to Elect and Effective Valley Congressman in 2011; overall, it has disclosed donations totalling more than $430,000. The PAC's other major contributors are media executives Peter Lowy of the Westfield Group and billionaire Stewart Resnick, who heads a pistachio empire. The donors also include $25,000 from mega-Democratic donor Jerry Katzenberg of DreamWorks. 

Sherman has made super PACs an issue in the race, repeatedly asking Berman in debates to sign a pledge against them. Sherman also filed a complaint with the Federal Election Commission alleging that Berman campaign has coordinated with the super PAC. The complaint involves political consultant Jerry Seedborg, whose firm was paid by the super PAC and the Berman campaign, according to disclosure reports filed with the FEC. 

Also worth noting: because of the Caifornia's new top-two primary system, which pits the two candidates who received the most primary votes in the general election regardless of party affiliation, these two Democrats are likely to face each other again in November.

California's 31st and 26th Districts

While the Sherman-Berman race may feature super PAC spending right up to its second round, there are two primary races in California—in districts where Republicans are favored in November—that have already attracted more outside money of tomorrow's primaries–each at over $1 million. Like Sherman-Berman, redistricting impacted both races. Five-term incumbent Gary Miller is facing off against Redlands mayor Pete Aguilar, a Democrat, which has become a proxy battle between the real estate industry and credit unions. Miller is a former developer and Aguilar is the former head of government relations at Arrowhead Credit Union. The real estate industry has the advantage, with the National Association of Realtors spending, via its political action committee and super PAC, some $800,000–more than the roughly $550,000 that the Miller campaign has spent this year. A super PAC created by the California and Nevada Credit Union League has spent about $160,000 supporting Aguilar, on top of about $230,000 spent by the Aguilar campaign so far. 

In California's 26th district, national Democrats are spending just to try to get their party member, state Rep. Julia Brownley, on the ballot in November. Because of the state's new top two primary system, independent Linda Parks may beat out Brownley to take on the favorite, Rep. Elton Gallegly. The House Majority PAC (a super PAC of House Democrats), Women Vote!, and the League of Conservation Voters have spent nearly $1 million to prevent that from happening. 

Parks has been backed by a measly $50,000 by a super PAC started in April called icPurple, Inc. (which originally filed under the name Independent Leaders, Inc.). The treasurer of that group is Tom Grueskin, who works in the consumer electronics field in the San Diego area, according to his LinkedIn profile.

New Jersey: Pascrell v. Rothman

Curiously, another high profile race pitting two Democrats against each other has not attracted any outside money. In blue northern New Jersey, Steven Rothman and Bill Pascrell have spent about $2.7 million from January through mid-May, the date of their last report. Pascrell has accused Rothman of being a disloyal Democrat because, rather than run in New Jersey's neighboring 5th district, Rep. Scott Garrett, a Republican, Rothman chose to take on Pascrell. Rothman, meanwhile, has run ads charging that Pascrell is anti-environment and suggesting he supports tax cuts for rich people.

New Mexico's 1st District

Another close race is a Democratic battle in New Mexico to replace Rep. Martin Heinrich, who is running for Senate. Two super PACs, Women Vote!–one of the biggest-spending super PACs in 2010–and Progressive Kick Independent Expenditures, have entered the fray. State Sen. Eric Griego is backed by Progressive Kick, which has spent over $110,000, either on TV, radio and Internet ads criticizing county commissioner Michele Lujan Grisham or to knock on doors to support Griego. Meanwhile, Women Vote! has has dropped about $100,000, mostly on pro-Grisham mailings. Progressives Kick is principally funded by Lawrence and Suzanne Hess of San Diego, Calif.—to the tune of $210,000. Lawrence owns a real estate management firm.

The campaigns have also turned nasty, with Griego alleging that Grisham was responsible for mistreating seniors while Grisham ran an ad suggesting Griego thinks he is above the law.

Montana

Montanans are also going to the polls Tuesday, voting in a Senate race expected to be close in the fall. The major parties' candidates, Rep.  Denny Rehberg, R-Mont., and Sen. Jon Tester, D-Mont, are expected to easily win their primaries. The race has already attracted nearly $700,000 of independent expenditures from outside groups, including over $400,000 from the 501c4 group Patriot Majority USA–which legally does not have to disclose its donors–backing Rehberg and $250,000 from the League of Conservation Voters backing Tester.