US presidential TV ad campaign spending soars since 2012

This year's US presidential election campaigns are breaking new ground not only for the tone of their messages but for how hard they're trying to get Americans to listen to them.

The volume of television advertising since January 2015 is up 122 percent from the same period four years ago, according to a new study by the Wesleyan Media Project released Thursday.

Presidential campaigns and outside groups have spent a total of $408 million on 480,000 ad airings compared with $120 million on fewer than 220,000 advertisements by this point in 2012.

A campaign ad paid for by Democratic presidential candidate Senator Bernie Sanders' campaign on TV in a hotel breakfast room in Des Moines, Iowa on November 16, 2015 ©Alex Wong (Getty/AFP/File)

Republicans are outspending Democrats, having shelled out two-thirds of the total amount so far from January 1, 2015 through May 8.

Republican campaigns are airing ads at a volume of 80 percent more than four years ago, the report says.

The Democratic campaigns are airing ads at a frequency of 1,500 percent more than in 2012 only because incumbent President Barack Obama faced no primary opponent then.

This time, Democratic presidential candidate Bernie Sanders has been promoted by the highest number of ads, nearly 125,000.

The Vermont senator is followed by Democratic front-runner Hillary Clinton, with 105,000 ads supporting her White House bid.

While more than 98 percent of Democratic Party spending was by the campaigns themselves, some 76 percent in the GOP race has come from outside groups, many of them so-called super PACs supporting single candidates, the study said.

More advertising hasn't necessarily translated into more votes, however.

"One remarkable aspect of this campaign is that the candidates who benefited from the most advertising did not necessarily fare well in the race," Wesleyan Media Project co-director Travis Ridout said in a statement. "Trump managed to become the presumptive Republican nominee in spite of being out-advertised. One reason for this is his amazing ability to attract free media."

While former Republican front-runner Jeb Bush has been ridiculed for spending some $130 million on his campaign before withdrawing from the race under relentless attack from Trump, the presumptive Republican nominee, Trump has used social media to amplify controversial messages analysts say are aimed at dominating coverage on national news media.

Trump -- whose campaign has paid for all advertising promoting him -- was sixth, behind both Democrats and former presidential candidates Marco Rubio, Ted Cruz and Bush.

Some 33,000 ads have backed the real estate tycoon on air.