Yet Mandel remains very much alive in Ohio, thanks to outside groups that have been lashing Democratic Sen. Sherrod Brown. This week, GOP outside spending in the race eclipsed the $10 million mark (and, unlike Mack, Mandel has proved adept at fundraising). One of the Republican groups attacking Brown in Ohio is Crossroads GPS, an affiliated arm of American Crossroads. The groups are prepared to spend a whopping $70 million dollars to help Republicans win control of the Senate this cycle. Senate Democratic contenders can't count on the same levels of support. The Democratic affiliated Majority PAC raised $5.4 million during the second quarter, which is about three times its previous quarterly haul. But the money Crossroads, Adelson, and other Republican groups and figures are prepared to spend on Senate races is simply in a different league. The expected disparity has spurred the Democratic candidates to work hard on their own fundraising. And it has paid off. In Virginia, former Democratic National Committee Chairman Tim Kaine outpaced former Republican Sen. George Allen once again last quarter. North Dakota Democratic nominee Heidi Heitkamp and Arizona Democratic nominee Richard Carmona each raised about $1 million in the second quarter, while Wisconsin Rep. Tammy Baldwin raised over $2 million. But impressive campaign fundraising still may not be enough to stave off defeat for the most vulnerable Democrats. In Missouri, Democratic Sen. Claire McCaskill raised an impressive $2.6 million during the second quarter and banked $3.6 million. And none of the three Republicans running against the first-term senator is a clear frontrunner. But GOP outside groups -- which McCaskill targeted in her first TV ad -- have already spent millions hitting her with negative ads, and promise to spend millions more in the fall. In the one race where outside groups have been a non-factor for the last few months because of a pact to keep them out, Democratic Challenger Elizabeth Warren has nearly pulled even with Republican Sen. Scott Brown in the cash on hand race (he ended the second period with $15.5 million while she finished with $13.5 million), a remarkable feat accomplished by raising funds at an unprecedented rate for the past three quarters. But what's true in Massachusetts isn't true in other places, where agreements imposing fines for outside group spending don't exist. And that's encouraging news for the Republican challengers struggling to keep pace with their Democratic opponents, who are doing everything in their power to mitigate the effects of a one-sided outside spending battle.