Four years ago this month, Priorities USA Action, the Democratic super PAC created by former staffers of President Barack Obama, dropped the first in a series of television commercials created to brand Mitt Romney as a heartless corporatist whose business deals enriched him at the expense of struggling Americans.

The initial negative advertising blitz, in tandem with Obama's presidential campaign, is now widely credited with decisively defining Romney to the electorate early on and damaging his reputation to a point of no return.

Fast-forward a full election cycle to the very same timespan, and Democrats again are seeking to stain a wealthy presumptive Republican nominee's image with a catalogue of callous commercials.

But 2016 is not 2012, and Donald Trump is no Mitt Romney. The New York City billionaire's omnipresent candidacy within a nonstop new media atmosphere raises considerable doubts about whether a similar strategy can be as effective.

"Trump has crafted his own image before his opponents have been able to do it," says Kathleen Hall Jamieson, director of the Annenberg Public Policy Center of the University of Pennsylvania. "Some of that is potentially negative, but people already know it. Romney was less well-known. The electorate's total exposure to Romney at this point was lower than the electorate's total exposure to Trump."

Priorities USA Action is attempting to pierce that theory with an advertising flight that is almost identical to what it produced in 2012. Four years ago, it put up $4 million in five battleground states – Colorado, Florida, Ohio, Pennsylvania and Virginia – to cast Romney's career atop Bain Capital as a venture only "to make money."

They're now in the midst of spending $6 million in four states – Ohio, Florida, Virginia and Nevada – framing Trump in a pair of spots as, according to a press release, "divisive, dangerous and offensive."

The group's buzziest 30-second advertisement, called "Speak," features a cast of women wearing white T-shirts emblazoned with Trump's head, mouthing the audio of some of Trump's most incendiary statements.

"Does she have a good body? No. Does she have a fat ass? Absolutely?" Trump is heard saying in one clip.

The rapid succession of lewd statements is designed to deem Trump unsuited for the nation's highest office. But a study of independent voters' reaction to the commercial by Ace Metrix found that while it grabbed attention, it fell below normal scores for agreement, relevance and watchability.

"Compared to the average politics ad, independents viewed this as less impactful than other ads that they'd seen. It's not really persuading the middle," says Peter Daboll, CEO of Ace Metrix, a California-based company that measures the impact of video advertising.

Ace Metrix provided U.S. News with a compilation of the verbatim comments by the self-identifying independents included in their focus group of 500 respondents. One male in his 50s called the spot "a hit piece on Donald Trump taking his words out of context." Another male in the 36- to 49-year-old bracket said, "Nobody's perfect. People need to lighten up and stop being so prudish."

An African-American woman in her 50s reacted by saying, "I've heard all of this before. It has nothing to do with the main issues of running the country." A female in her 50s said, "I thought it was a foul ad. I know what has been said and I don't need to be reminded. I do not like dirty politics."

Daboll surmised that editing the audio clips of Trump over the women might have hurt the advertisement's credibility with some voters.

"By using Trump's voice it might've backfired a bit, instead of having regular women talking. It looked like a smear," he says.

Jamieson believes that Trump's aggressive instinct to rapidly respond in-person to any and all negative charges has provided him with a layer of defensive armor that Romney lacked.

"Trump has more rebuttal structure out there on this than Romney did on the Bain Capital charges," she says. "Because Trump has been constantly in the media, every time this stuff with women comes up, Trump either distracted or created a new context around it. They've moved the rebuttal material out very quickly. Reporters have every opportunity to interview Trump that they want. Romney was not in the media as Trump is and didn't have opportunities to move his material. He wasn't doing many interviews."

Try to remember a Romney news conference or rally that was taken live during the spring for more than a half-hour on all three cable news channels. Now try to think of a 48-hour period in which Trump didn't command that type of ceaseless attention since the beginning of the primaries.

"Trump has exploited the dispositions of the media brilliantly in order to minimize his vulnerability to charges," Jamieson says. "I don't know anyone else who is capable of doing what Trump is doing. It works for him because he's novel, he's unpredictable, he's interesting."

Democrats acknowledge that Trump is certainly a completely different foe than Romney, but are still married to the idea that the fundamental rules of modern-day politics apply – the chief one being that they must seek to define their opponent before the general election news cycle becomes oversaturated.

"Trump is well-known but that doesn't mean he's been defined as a candidate," says Ben LaBolt, a Democratic strategist who served as Obama's national press secretary in the 2012 campaign. "There's a window now entering the general election to do so, but the window is now. In an era of super PACs, there's diminishing returns on ads heading into Election Day because the airwaves get so flooded."

While the first Priorities USA Action spots have focused on Trump's temperament, Democratic operatives foresee an eventual escalating air war that aims to puncture the heart of his perceived strength: his business acumen.

Not dissimilar to the onslaught against Romney and his time at Bain, Trump is likely to confront scathing reprisals of his own failed business deals and real estate endeavors that left ordinary people on the hook, all while he tried to line his own pockets.

"It'll be how he treats workers and it will matter to independents," says Bob Shrum, an adviser to the presidential campaigns of John Kerry and Al Gore. "People have some sense of the stuff about women; to be reminded of it is useful. I think that's only the first stage. I think people don't know much about his business record at all."

But in an environment in which Trump can command or, more crucially, redirect a news cycle with a single series of late-night tweets, generating a consistently resonant line of attack on the airwaves will be a challenge to anyone attempting to leave a mark on The Donald.

Trump has been a master at altering the storyline by always being willing to up the ante on the outrageous, or by opening a line of fire on a fresh new target.

John Sides – a George Washington University political science professor who studied the qualitative data of the 2012 election to separate events that earned media attention from what actually swayed the outcome of the presidential race – argues that the effect of ads usually wears off relatively quickly.

Only when an ad engenders sustained free media coverage can it drive a compelling narrative, Sides says, and that usually only occurs when there's new information being introduced about a candidate.