In their stump speeches, advertising, and meet-and-greets, the top 2020 Democratic presidential candidates are eagerly sniping at each other as they criss cross the Granite state in the final days before the critical New Hampshire Democratic primary on Tuesday.

Yet one person is conspicuously absent. Looming over the race is fellow candidate and former New York mayor Michael Bloomberg, a billionaire who has decided to completely forgo New Hampshire and all other early primary states to instead invest heavily in the crucial set of Super Tuesday states that vote on 3 March – an unconventional and risky strategy.

Bloomberg is “spending millions to buy the election,” Sanders warned this week.

“How do we feel about living in so-called democracy when a billionaire multiple time over can do that? How do we feel when we have candidates in the Democratic party taking money from billionaires?”

Having spent at least $10m on a 60-second advert in the Super Bowl last week, Bloomberg has since capitalised on the chaos from the Iowa caucuses, in which both the self-described Democratic socialist Vermont senator Bernie Sanders and the moderate former South Bend mayor Pete Buttigieg declared victories, though the race was officially too close to call.

The former vice-president Joe Biden, who had been seen as the frontrunner among the moderate candidates, trailed in fourth and called the Iowa result a “gut punch”. Bloomberg, who has cast himself as the moderate to beat Trump and banked on Biden falling behind, responded by doubling his advertising spending.

At a press conference about the Iowa results, Sanders said it was “an absolute outrage” that Bloomberg would also likely qualify for the next televised presidential debate in Nevada later this month, when he is not even on the ballot there. “I guess if you’re worth $55b you can get the rules changed to debate.”

Besides eschewing the early primary states, Bloomberg has opted to self-fund his campaign and has poured in over $188m. He has also quietly been working to bottleneck funding avenues for other the campaigns of other candidates by urging deep pocketed donors to give to Democratic committees instead.

Michael Bloomberg speaks at a campaign event Wednesday in Providence, Rhode Island. Photograph: David Goldman/AP

While other candidates have doggedly toured New Hampshire and early primary states, Bloomberg has been campaigning in locales that are later on the voting calendar, like Oklahoma, California, Colorado, and Pennsylvania. Bloomberg has already visited every Super Tuesday state in a two-month period.

“Since day one, our campaign has been focused on building a nationwide operation that is engaging with voters daily about Mike’s record on key issues and why he’s the strongest Democrat in the race,” said Dan Kanninen, Bloomberg’s states director.

“While other candidates focus on New Hampshire, we’re committed to winning delegates on Super Tuesday and beating Donald Trump in November.”

His campaign has ballooned to 2,100 people, with 1,700 of them in the states and 400 at the campaign’s headquarters in New York. Other campaigns have staffs in the hundreds. By the end of this week the campaign says it will have opened 125 offices.

Whichever candidate emerges as the presumptive frontrunner after the early primary contests end with the South Carolina primary on 29 February, they will then have to face a moneyed Bloomberg effectively lying in wait to attack.

Kathy Sullivan, a former New Hampshire Democratic party chairwoman who has endorsed the Massachusetts senator Elizabeth Warren, who placed third in Iowa, said even though Bloomberg isn’t campaigning in New Hampshire his presence is still felt.

“We see the ads here in New Hampshire although he’s not on the ballot here,” Sullivan said. “I think he will be a major factor going forward because of just the amount of money he’s spending and because he’s playing in all those Super Tuesday states.”

And some New Hampshire voters are intrigued. Bill Mauser, a US Navy veteran who attended an event for Buttigieg this week, called Bloomberg an “interesting prospect”.

“He’s a very accomplished self-made man, doesn’t have a retail politics approach,” Mauser said. “He certainly has chops but the question is, are his chops good enough to really qualify him to be a leader? So how do I feel about him? I’m open to what he has to say.”

For his rivals, the critique of Bloomberg is almost always the same: that he’s buying his way into the presidential election.

During Friday night’s televised Democratic debate, Warren was asked about the seeming unlimited amount of spending behind the former New York mayor’s candidacy. She said: “I don’t think anyone should be able to buy their way into a nomination or to be president of the United States.”

During an appearance on CNN’s State of the Union in January, the Minnesota senator Amy Klobuchar, another Democratic presidential candidate, likened Bloomberg to Donald Trump.

“When people look at the White House and see this multimillionaire messing up so many things,” Klobuchar said, “I don’t think they think, ‘Oh, we need someone richer.’ I think you have to earn votes, not buy them.”

But Bloomberg’s strategy is causing some Democrats to recalibrate how they think of the primary calendar. Maura Keefe, a Democratic strategist and former chief of staff to the New Hampshire senator Jeanne Shaheen, said Bloomberg’s massive spending calls into question just how valuable winning an early primary state is these days.

“The money piece is what’s the monetary value of winning New Hampshire or winning and coming in second,” Keefe said. “What is the value of that free press? That attention? We’re already seeing the value of Buttigieg’s surprise in Iowa for him here. And if somebody surprised in New Hampshire by beating expectations there’s a monetary value in that.””

But Keefe added that she didn’t see Bloomberg as a trending topic among votersyet, just “a topic of conversation certainly amongst the media and maybe political elites”.