Just how much does it cost to buy the US presidency? $800m? A billion? A couple of billion?

It looks as if Michael Bloomberg is trying to find out. Since entering the race in November, he has spent an unprecedented amount of money trying to win the Democratic nomination. In less than three months, Bloomberg, who is worth about $60bn (£46bn), has spent about $320m on TV advertising alone – more than double the amount Tom Steyer, the other billionaire running and the second-biggest spender, has shelled out on ads. Since January, Bloomberg has spent more on Facebook ads than Joe Biden, Bernie Sanders, Pete Buttigieg and Elizabeth Warren combined.

His strategy (spend, spend, spend and see what sticks) seems to be paying off. He has surged to third place in some opinion polls, despite skipping Iowa and New Hampshire, and has been racking up endorsements from people including the mayor of Washington DC and the former ABC News anchor Sam Donaldson. It is still early, but he may be the candidate who faces Donald Trump in the general election.

If these two billionaires end up battling it out for the presidency, I am not sure it matters who wins in November. Democracy will have lost. We will have entered a new age of American oligarchy. A dangerous precedent will have been set. Money and politics will become even more intertwined. We might not see a non-billionaire become president again for a very long time.

“Better Bloomberg than Trump!” some will protest. There is a strand of thinking among many liberals that it doesn’t matter who beats Trump, or how, just as long as they beat him. Bloomberg has his flaws, the logic goes, but he is exponentially better than Trump. Sure, he has spearheaded racist policies such as stop-and-frisk, but he has also spent lots of money tackling gun violence and the climate crisis. And, unlike the reality TV star ruining the country, Bloomberg has political experience. Indeed, as a former mayor of New York City (population 8.5 million), he is far more qualified for the job than Buttigieg, the ex-mayor of South Bend, Indiana (population 102,000).

Whether Bloomberg is a “better” billionaire than Trump is not the point. Democracy is broken if someone can parachute into an election at the last minute and spend unlimited amounts – there are no restrictions on self-financing – transforming themselves into a viable candidate. Democracy is broken when a billionaire can, as Bernie Sanders put it, attempt to “buy this election”.

Some may argue that buying a ton of ads is not the same as buying an election, particularly as the outsized influence of money in US politics is nothing new. According to a 2014 study by two political scientists, “economic elites and organised groups representing business interests have substantial independent impacts on US government policy”, while average people “have little or no independent influence”. Is there much difference between a billionaire self-funding and a candidate raising money from billionaires?

Yes. I don’t think you can underestimate the optics of Bloomberg’s unapologetic spending spree. It lifts the veil on money in politics. It sends a dispiriting message to an already disillusioned electorate that politics is a swamp where ordinary people are not represented and where influence is bought. Even if Bloomberg doesn’t win the nomination, it seems inevitable that his success so far will pave the way for more billionaires. Bezos 2024? Zuckerberg 2028? It looks increasingly likely.

•Arwa Mahdawi is a Guardian columnist