When the latest round of polls in key states showed vulnerable Democratic senators holding their own and the GOP’s dream candidate, Rep. Tom Cotton, an Iraq veteran and Harvard grad, down 10 points in his race against Arkansas Senator Mark Pryor, Republicans blamed the Senate Majority PAC as the chief culprit in shifting the landscape and upending the numbers.

Formed in 2011 and staffed by former aides to Senate Majority Leader Harry Reid, it has been spending heavily and early in races that will determine which party controls the Senate after November, and of course whether Reid keeps his job as leader.

Spending early to define the opposing candidate in negative terms is known as the Romney strategy. It’s what the Obama campaign did in 2012 with a flood of money before Romney even secured the nomination, successfully defining him over the airwaves as a rich and uncaring corporatist.

You could say freshman Rep. Cotton is the Romney in this cycle. A Senate Majority PAC ad launched in March says, “Corporate special interests are spending millions to smear Mark Pryor and elect Tom Cotton. Why? Before Congress, Cotton got paid handsomely working for insurance companies,” says the narrator. The Washington Post fact-checker awarded the ad four Pinocchios for stretching the truth, noting that Cotton did not work directly for an insurance company. He was employed by the global consulting firm, McKinsey & Company, and lists insurance among the industries he assisted on his Facebook page.

A spokesman for Senate Majority PAC says all their ads are fact-checked and screened by lawyers, who must have found enough of what Stephen Colbert once dubbed “truthiness” to green-light the ad. Besides, getting facts right is an outdated notion; nobody is handing out medals for accuracy. “They’re putting up things that don’t pass the smell test but are effective, and there’s no penalty,” says Jennifer Duffy with the nonpartisan Cook Political Report. “There’s a line you can’t cross, but no one knows where the heck that line is.” Americans for Prosperity (AFP), funded by the Koch Brothers, has multiple Pinocchios for its ads, mainly for distorting Obamacare.

Senate Majority PAC is spending in nine states, and is in the middle of a two-week, $850,000 campaign against Thom Tillis, the Republican challenger in North Carolina. The night Tillis won his primary, Senate Majority PAC was in the rear of the ballroom filming an ad about all that’s wrong with Tillis from the Democratic perspective. A female narrator speaks in hushed tones to the camera as Tillis is heard in the background.

Senate Majority has spent more money in North Carolina than any other state, and they’ve been playing catch-up with AFP, which has spent some $10 million to $13 million over the last year attacking Democratic Sen. Kay Hagan. “They had to go up because there was so much Republican money in some of these states,” says Duffy. “They helped stop the bleeding. They spent a lot in North Carolina, but Kay Hagan is still in a lot of trouble.”

Louisiana Democrat Mary Landrieu saw a double-digit spike in her disapproval rating in the last six to nine months, says Duffy. The reason: an onslaught of AFP ads tying her to Obamacare. Senate Majority PAC retaliated with ads that tie Landrieu’s likely rival, Rep. Bill Cassidy, to the Koch brothers, saying the brothers “funded the fight to let flood insurance premiums soar… Now they’re spending millions to buy a Senate seat for Bill Cassidy so he can fight for them.” Cassidy has not repudiated the Koch brothers, and would likely be more of an ally for them and their business interests than Landrieu, but he supported the flood insurance reform bill that the Koch brothers opposed, which is why Politifact called the ad “mostly false.” Put another way, it’s a partly true ad that has put Landrieu back into the game. The latest poll shows a tied race with Landrieu almost at 50 percent.

This midterm cycle is distinguished by the amount of money, and the sloppy truth-telling. “In the old days, groups would have to make choices—spend early or spend late, when people are making their decisions. There’s so much money now they say, what the heck, spend early, see if it moves the needle, and if it doesn’t, you can still raise more money,” says Stuart Rothenberg with the nonpartisan Rothenberg Political Report. “Everybody’s fast and loose with the facts these days. This is the current system, and the Senate Majority PAC has been a big player.”

In Michigan, a Senate seat that Democrats once took for granted is now up for grabs with the retirement of Sen. Carl Levin. Democratic Rep. Gary Peters faces a strong challenge from Secretary of State Terri Lynn Land. Senate Majority PAC doesn’t mention the Koch brothers by name in their anti-Land ad, but allude to out-of-state corporate interests and billionaires paying for her race. Another ad attempts to tie Land to the “war on women” meme that worked so well for Democrats in 2012.

Land countered with an ad saying, “Really?” “I might know a little more about women than Gary Peters.” A good spot, but substance-free, and Senate Majority PAC charged Land “has it backwards,” that she opposes common forms of contraception and would ban abortion even in cases of rape and incest.

It’s only May and voters living in the states where Senate Majority PAC is spending (North Carolina, Louisiana, Arkansas, Michigan, Kentucky, Iowa, Colorado, New Hampshire and Massachusetts) will be saturated with negative ads. “I’m always amazed anyone believes what they see,” says Larry Sabato, professor of politics at the University of Virginia. “Even the positive spots with grandmas and spouses and kids, I wonder what they’re really like behind the scenes.” Voters may be skeptical, but the numbers don’t lie, these ads work, and mega-donors emboldened by loosened campaign finance rules, are flooding the zone.