During the 2012 election, Republican presidential candidate Mitt Romney's infamous "47 percent" remarks gave Romney's liberal opponents a way to easily characterize the candidate as elitist and out of touch.
This year, as Democrats put forward a midterm campaign pitch focused on pocketbook issues, they don't have a single figure like Romney to hold up as a symbol of the GOP's supposed shortcomings. Instead, they've zeroed in on a pair of rich conservatives: the billionaire brothers Charles and David Koch.
Democrats and their allies have spent a better part of the year hammering Koch-affiliated organizations for injecting vast sums of money into conservative political campaigns. They've also made a concerted effort to tie Republican candidates to the brothers, who lead the energy and manufacturing conglomerate Koch Industries. This week, liberals say they found this year's "47 percent moment."
As first reported by The Nation magazine and the Huffington Post, a handful of Republicans recently attended a conference hosted by the Koch brothers, where they hailed their deep-pocketed supporters for propelling their political careers.
In remarks that were secretly recorded, Iowa Republican Senate candidate Joni Ernst can be heard saying that she started out as "a little-known state senator from a very rural part of Iowa... But the exposure to this group and to this network and the opportunity to meet so many of you, that really started my trajectory."
Senate Minority Leader Mitch McConnell, R-Kentucky, meanwhile, said it was "the worst day on my political life" when the McCain-Feingold Act passed in 2002, reining in political spending.
Liberal grassroots groups like MoveOn.org and Democracy for America called it the "47 percent moment" they've been waiting for.
"This is a golden opportunity to make sure the American public understands just how extreme and out-of-touch the leadership of the Republican Party is--and how beholden to these right-wing billionaires they've become," MoveOn said in an email sent to its supporters Wednesday. The group is seeking donations to help fund ads using those recordings in Kentucky, Iowa and Colorado.
Clearly, the Koch brothers, who have stayed out of the spotlight while backing groups like Americans for Prosperity, do not have the name recognition of Mitt Romney.
A Wall Street Journal/NBC poll conducted in April, around the time Senate Majority Leader Harry Reid, D-Nevada, charged that Senate Republicans "are addicted to Koch," found that about half the nation didn't know who the Koch brothers were. Twenty percent of Americans said they had neutral feelings about the Koch brothers, while 21 percent had negative feelings and 10 percent had positive feelings.
MoveOn Campaign Director Vicki Kaplan told CBS News that their anti-Koch ads are "about more than just the Koch brothers.
"Part of what these tapes reveal is the kind of policy agenda that candidates who are following the lead of the Koch brothers are pushing," she said, such as opposition to minimum wage increases or supporting cuts to entitlement programs.
"Those are all things that huge numbers of voters support," Kaplan continued. "Revealing that agenda and knowing that out-of-state oil billionaires are supporting that push makes voters even more skeptical" of the GOP agenda.
Brad Woodhouse, president of American Bridge 21st Century, a Democratic opposition research super PAC, said that if voters aren't aware of who the Koch brothers are, groups like his have a "fiduciary responsibility" to inform them.
"Whether [anti-Koch ads] are effective or not, these people will spend more money trying to elect Republicans than the Republican party will spend," he said.
During the 2012 campaign, according to one analysis, a network of 17 Koch-backed entities raised at least $407 million, outpacing other independent groups on the right and at least matching labor union coalitions on the left.
There's evidence that groups opposed to the Koch brothers are having an impact with their campaigns. It's unclear, however, whether their influence comes from linking GOP candidates to the Koch brothers or simply from spending large sums of money.
In Michigan, where the open Senate race to replace retiring Democratic Sen. Carl Levin is considered a toss-up, a Democratic super PAC has invested a considerable sum to tie Republican candidate Terri Lynn Land to the Koch brothers. The group, called the Senate Majority PAC, has spent more than $3 million in the Michigan Senate race, far outpacing any other outside group that's invested in the race so far. It has run ads charging that Land is "helping the powerful at our expense."
A recent poll, commissioned by the League of Conservation Voters and the labor union AFSCME, shows the Democrat in the race, Rep. Gary Peters, is leading. It also shows that more than half of Michigan voters have heard of the Koch brothers, while just 33 percent haven't.
The poll, commissioned by left-leaning groups, should be viewed with some skepticism. But in another sign that the anti-Koch campaign may be having some impact there, one Koch-related group has reportedly cancelled $1.1 million in television ads it planned to run in Michigan.
Meanwhile, Alaska's Republican Senate candidate Dan Sullivan has also been the target of anti-Koch ads. The Koch-backed group Americans for Prosperity is running a $1 million ad campaign on his behalf. However, outside spending in Alaska has so far come largely from groups supporting Democratic Sen. Mark Begich.
Sullivan recently released an ad calling on Begich to agree to "stop all the mud-slinging by outsiders."
But even if there is some Koch backlash, it's not completely stopping Republicans from associating themselves with the Kochs.
Several potential 2016 GOP presidential candidates such as Sens. Ted Cruz and Rand Paul, Gov. Rick Perry and Ben Carson will speak at a weekend summit in Dallas beginning Friday organized by Americans for Prosperity.