Updated

Given the myriad world crises and domestic troubles facing the United States, Americans might be surprised to learn our single greatest threat is... the Koch brothers? At least, Senate Majority Leader Harry Reid may think so, judging from the barrage of attacks he's hurled at them.

In recent weeks, his invectives have ranged from "Senate Republicans...are addicted to Koch, “ to "These two brothers don't like government,” "The Koch Brothers and other moneyed interests are influencing the political process for their own benefit," and "The Republicans in the Senate go along with what the Koch brothers want."

But a recent George Washington University/Battleground Poll found that 52 percent of Americans don't even know who the Kochs are.

Charles and David Koch are libertarian billionaires who largely made their fortune in the oil business. Their philanthropic giving ranges from such causes as cancer research and the New York City Ballet to drug decriminalization, gay marriage and the repeal of ObamaCare.

That last cause may explain Reid's pre-occupation. "The strategy behind attacking the Koch brothers and others is basic class warfare," says Charlie Hurt, a columnist for the Washington Times. "They know they can't win the argument about ObamaCare because ObamaCare presently is highly unpopular."

The Kochs are blanketing key battleground states with a $30 million ad blitz aimed at Democratic candidates who voted for ObamaCare, including Sens. Kay Hagan of North Carolina, Mark Begich of Alaska, Mary Landrieu of Louisiana, Mark Pryor of Arkansas, Jeanne Shaheen of New Hampshire and Mark Udall of Colorado. Thirteen vulnerable House members have also been the object of relentless Koch attack ads on cable, broadcast and the Internet.

A new USA Today poll shows that how a candidate stands on ObamaCare will be an important issue for 84 percent of registered voters. More importantly, the rate shock of rising insurance premiums may be driving a new voter anger. The poll shows support for the law has fallen to 37 percent, the lowest since the summer of 2010, when members of Congress were besieged by ObamaCare critics at town halls across America.

It helps to illustrate why Harry Reid and vulnerable Democrats may be worried the Koch strategy is working. "They're saying these rich men are much like Russians," says Fox News contributor Juan Williams. "They're trying to control the political process , they're trying buy an election for themselves and control the U.S. Senate. This, to me, reminds so much what President Obama did successfully in demonizing Bain Capital and Mitt Romney, " he adds.

OpenSecrets.org, from the nonpartisan Center for Responsive Politics, reports that Koch Industries ranks only 59 on the list of biggest campaign donors over the last 25 years. The top spot belongs to "ActBlue" - a political action committee that donated over $100 million - 99 percent of it to Democratic candidates.