The candidates in the top 1 percent have accounted for about 78 percent of the ad spending in the presidential race so far, according to new numbers.

The two self-funding billionaires in the Democratic primary, former New York City Mayor Mike Bloomberg and activist business executive Tom Steyer, have spent the most by far — a combined $320 million, out of $409.8 million spent in the presidential contest up to Jan. 13.

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That massive investment has boosted Bloomberg and Steyer in national and state polls, but not enough to break into the quartet of front-runners: former Vice President Joe Biden; former South Bend, Ind., Mayor Pete Buttigieg; Vermont Sen. Bernie Sanders; and Massachusetts Sen. Elizabeth Warren.

The data from Advertising Analytics was provided to NPR for all ad spending through Monday. It doesn't include reserved ad time in the coming weeks, which is expected to crescendo as the first votes draw close. But it still captures the massive spending disparities in the field of current candidates.

The top four candidates are neck and neck in polls for the Iowa caucuses, now just over two weeks away on Feb. 3. Steyer has spent the most there, but Buttigieg's fundraising prowess helped him make a major investment in the state. Through Monday, he'd spent $8 million on advertising in Iowa, including $5.9 million on broadcast television and $2 million on cable.

Sanders isn't far behind, with $7.2 million spent in Iowa. Warren ($3.9 million) and Biden ($2.9 million) are further back. Unite the Country, a superPAC backing Biden, has spent over $2.1 million on his behalf, which combined with his own total makes him the beneficiary of the fourth-highest spending.

Nonprofit executive Andrew Yang has actually spent more than Biden (when looking at candidate money alone, without superPACs) and Warren in Iowa, with $5 million in the state on TV and digital ads. He's also spent $2.2 million on ads in New Hampshire, making him the fourth top-spending candidate there. Minnesota Sen. Amy Klobuchar needs a strong showing in Iowa, and she has spent $2.2 million on ads there.

The first primary state, voting on Feb. 11., has seen less attention statewide from candidates compared to the first caucus state, with $44.9 million being spent on ads in Iowa compared to $27.7 in New Hampshire.

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The biggest takeaway still remains the massive investments by Steyer and Bloomberg — and watching how little that gamble has paid off. Each billionaire has taken a different tack when it comes to their primary strategy and ad buying.

Steyer, a former hedge fund executive and environmentalist, put millions into ad blitzes in early states since he reversed his decision not to run in July. As a result, he's the top spender in both Iowa (over $13.9 million) and New Hampshire (more than $15.9 million). The vast majority of his spending has been on broadcast TV, but notably he's spent a chunk as well on digital advertising — $1.8 million in Iowa and $1.54 million in New Hampshire. It was enough to get him on the debate stage this week, but still not to break into the very top tier. Overall, Steyer has spent nearly $124 million nationally since July.

That's been eclipsed by Bloomberg, who has spent about $196.2 million just since he got in the race in late November. And $163.8 million of that has been on broadcast TV, with a still substantial investment in digital ($22.1 million) and cable ($10.2 million). Bloomberg isn't contesting early states like Iowa and New Hampshire. Instead, he's pursuing a more nationalized strategy by targeting delegate-rich states, including Texas and California, that will hold primaries on Super Tuesday, March 3, and beyond. That's a risky tack that has failed in the past, though it hasn't been tried before by a candidate with virtually unlimited deep pockets.

While the dozen Democrats left in the race are still jockeying for the nomination, President Trump and the outside groups supporting him have been spending heavily on TV and digital advertising, too. Trump's official reelection committee Trump for President has already spent $14.75 million on ads, including around $4.4 million on broadcast TV and $9 million on digital ads. His joint fundraising committee has also spent another $26.6 million on digital ads alone. And he's set to spend $10 million on a Super Bowl ad next month, the day before the Iowa caucuses. (Bloomberg is advertising during the major sporting event too).

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