The airwaves this year have been flooded with political ads from third party groups, thanks to a set of 2010 Supreme Court rulings including the Citizens United decision, which ushered in a new era of unlimited political spending in America.
While most of the spotlight this year is on the presidential election, outside groups have the potential to make a bigger impact in congressional races, where a six-figure ad buy -- and especially a seven-figure investment -- can go a long way.
The nonpartisan, nonprofit Center for Responsive Politics tracks outside spending in congressional races. Based on their data, here's a look at three House races and three Senate races where outside groups are spending the most to influence the outcome.
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