But good luck tracking down who gave the money to ATR and VoteVets to finance those attacks in the first place. The groups don't have to tell you - and they won't.
Aside from the rise of the tea party movement, the major story in this year's midterm election campaign has been the sheer volume of cash that special-interest groups are pumping into House and Senate races across the country, much of it from anonymous donors.
These outside groups - unions, business associations, and ideological organizations - have doubled their spending on political advertisements and messaging compared with the 2006 midterm election, according to a tally released Friday by the Center for Responsive Politics, a watchdog group.
So far the outside spending has overwhelmingly favored Republicans, and Democrats, including President Obama, have used it as a war cry in their effort to maintain control of both houses of Congress on Nov. 2, warning that unaccountable corporations are threatening democracy.
The spending, experts say, has been driven in part by the January U.S. Supreme Court case Citizens United v. Federal Election Commission, which struck down long-standing prohibitions on the use of corporate and union cash in federal elections, as well as other legal developments that had already weakened the restrictions.
And of course, Republicans are riding high in the polls, with conservatives highly motivated to oppose Democratic policies that they consider antibusiness.
"Citizens United made it crystal clear that corporations and unions could spend their money directly on federal elections, and that's sort of a Good Housekeeping seal of approval that made them comfortable doing so," said Trevor Potter, an election lawyer with Caplin & Drysdale in Washington who was Sen. John McCain's general counsel in the 2008 presidential campaign and is a former chairman of the Federal Election Commission.
