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Michael Bloomberg could spend $1 billion or more in his quest to beat President Donald Trump — and experts and consultants in both parties say that unprecedented sum could tip a close presidential election.

"He'd be a super super PAC," said Bob Shrum, a longtime Democratic strategist. "Obviously, it makes a big difference. If he's going to spend a billion dollars, I see no way that Republicans could match that."

Bloomberg hasn't said exactly how much he’s willing to reach into his own pockets to unseat Trump, but he's estimated to be worth more than $50 billion and has already pledged to keep tapping his personal war chest to help Democrats defeat Trump, even if he's not the party’s nominee.

Some of Bloomberg's TV ads look like they're from a Democratic super PAC, focusing more on attacking Trump than boosting himself.

"The straight answer is that nobody has any idea what that would do, because no one has talked about spending that kind of money in a presidential race," said Whit Ayers, a leading Republican pollster who runs North Star Opinion Research. "It's an absolutely breathtaking amount of money."

Trump may have reason to be concerned about his fellow New York billionaire's money, but whether he's afraid or not, Bloomberg does seem to have gotten under the president's skin. After Bloomberg aide Kevin Sheekey appeared last week on "Fox and Friends," the Fox News morning show Trump is known to watch regularly, to debut a new ad hitting Trump, the president fired off a series of tweets attacking the man he called "Mini" Mike Bloomberg (the former mayor once described himself as 5-foot-7, but has also been listed as 5-foot-8).

Mini Mike Bloomberg is playing poker with his foolhardy and unsuspecting Democrat rivals. He says that if he loses (he really means when!) in the primaries, he will spend money helping whoever the Democrat nominee is. By doing this, he figures, they won’t hit him as hard.... — Donald J. Trump (@realDonaldTrump) January 23, 2020

The conventional wisdom among political insiders is that campaign spending, which primarily goes toward advertising, eventually reaches a point of diminishing returns. "But no one has really tested the proposition," Ayers said.

History shows money doesn't always win elections, but it often does.

In the 2018 midterms, top-spending House candidates won 88.8 percent of their races, according to the Center for Responsive Politics. And in 2016, their win rate was 95 percent.

"Money is the No. 1 factor in most elections," said former Rep. Carlos Curbelo, a Republican from Florida who, until the 2018 blue wave sent him packing, represented a Democratic-leaning district that includes Miami. "If you look back at the data, candidates that have the most resources at their disposal tend to win."

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Curbelo said Bloomberg's ads are already ubiquitous in Florida, a state so big and expensive to advertise in that national Republican and Democratic party groups often don't bother.

"You can't watch a football game without seeing him," Curbelo said of Bloomberg.

Speaking of which, viewers of next Sunday's Super Bowl, one of the largest TV audiences of the year, will see a 60-second Bloomberg spot — at an estimated cost of $10 million. Trump and the Republican National Committee are building an unprecedented war chest of their own and plan to deploy some of that to run their own Super Bowl ad, which his campaign said cost $10 million.

With the country deeply polarized, almost everyone expects the 2020 election to be a close race, decided on the margins in a handful of now-familiar Electoral College swing states, where Trump won by just tens of thousands of votes.

And tight races are where money can make a real difference, according to a growing body of academic research.

"A lot of ads can potentially swing an election that is close," said Jörg Spenkuch of Northwestern University, who conducted one of the most-cited studies on the impact of political advertising. "But ads are probably not effective enough to change the outcome of a race that wasn't close to begin with."

And how money gets spent can be just as important as how much. Research suggests that a lot of it is wasted. A 2017 analysis of 49 field experiments testing various campaign tactics, such as canvassing door-to-door, having volunteers make phone calls, and sending direct mail found an "average effect of zero in general elections."

But Stanford University's David Broockman, who conducted that study, said the impact of spending "in the context of a close election can still be very important."

Liam Donovan, a Republican consultant, said that "money is always going to matter at the margin," before ticking off a string of caveats.

For instance, if Bloomberg is not the Democrats' choice for president, will his spending reinforce or clash with the nominee's message and strategy? What if the nominee is Sen. Bernie Sanders, I-Vt., whose campaign is all about challenging the power of billionaires like Bloomberg?

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Is there even a way to effectively spend another billion or $2 billion in a money-drenched election year? "There's only so much airtime you can buy," Donovan noted.

Democrats will have plenty of money no matter what, said Tara McGowan, the founder of the Democratic digital group Acronym.

"Of course resources matter, but I don't believe that you can simply buy your way into the White House with unlimited dollars without also having a compelling vision a majority of voters want to align themselves with — and for democracy's sake, I sincerely hope that we don't see this proven wrong this year," she said.

Time will be a big problem for Democrats, since they can't start running against Trump in earnest until after their primary contest is sorted out. That begins for real on Feb. 3 with the Iowa caucuses.

Bloomberg has sought to address that by running ads hitting Trump in swing states now — such as a new one on the president's reported belittling of military generals that seemed to infuriate the president.

Jim McLaughlin, a Republican strategist who worked as a consultant on Bloomberg's mayoral campaigns, doubts Bloomberg will really spend nine figures this year, suspecting he is dangling the promise of the massive payout mainly to curry favor with Democrats.

"Do I think he can spend $2 billion? Of course. Do I think he will? No," McLaughlin said.

And he questioned the impact of that money, either way.

After all, the most expensive presidential campaign in history was Hillary Clinton's in 2016, and she wasn't able to stop Trump, though she did win the popular vote. She spent almost twice what Trump did per electoral vote won.

"Donald Trump was significantly outspent," McLaughlin said, "and at the end of the day, it didn't matter."