Mark Green was a young, vigorous, popular progressive who won the Democratic primary for mayor in 2001. New York City is overwhelmingly Democratic, and usually the Democratic nomination is enough to assure election.

But Mark Green faced an unusual Republican opponent, billionaire MIchael Bloomberg. No one knew much about Bloomberg, but he had the endorsement of Republican Mayor Rudy Guiliani, who had turned into a symbol of resilience and heroism after the devastating attack of September 11, 2001.

Green is now supporting Elizabeth Warren.

Mark Green writes here about what happened next in 2001.

Three weeks before the New York mayoral election in November of 2001, I got a call from Mark Mellman, the pollster working on my race against Michael Bloomberg.

“Well, I have good and bad news. The good news is that I’ve never had a client 20 points ahead this late in a campaign who lost. The bad news is that Bloomberg is spending a million dollars a day — not a month but a day — and gaining a point a day.” I quickly did the math and shuddered.

I lost the race by a margin of 50% to 48%, after being outspent $73.9 million to $16.3 million. Ironically, I raised more money than any other U.S. mayoral candidate in history, making 30,000 phone calls and receiving 11,000 contributions. But Mike, who didn’t have to make phone calls, spent the most money ever on a mayoral campaign. He simply wrote checks.

It’s no great surprise that after buying the mayoralty, Bloomberg decided to see if he could do the same with the presidency. There have been other self-funded candidates, of course, and they have all failed. Ross Perot spent $79 million in 1992 and Steve Forbes $60 million in 2000.

But if Mike gets the nomination, his spending already has dwarfed what they spent. He is a bank posing as a person.

I know what that looks like. In the closing weeks of our 2001 race, I had the helpless feeling that there was no strategy that could counter his spending. Everywhere I went I saw or heard a Bloomberg ad: in between innings during the Yankees’ World Series games, on hip-hop stations, on walls in Chinatown, on the rotating billboard at a Knicks game, on mailings that piled up in the lobbies of buildings across the city. He even sent small radios with his name on them….

Bloomberg does have some solid liberal credibility — on climate, guns and public health — but on many core issues his record is a liability. He has called Social Security “a Ponzi Scheme.” He opposed raising the minimum wage. He blamed the 2008 Great Recession, in part, on laws against predatory lending. He denounced Obamacare and Dodd-Frank. He enthusiastically endorsed the Bush-Cheney ticket in 2004, was an apologist for the Russian takeover of Crimea and has a long record of making demeaning comments about women. And, as late as last year, he was still advocating a “stop-and-frisk” approach and defending his record on the practice.

Given Bloomberg’s shaky performance in the Nevada debate, it’s hard to feel confident he can reassure liberal Democrats on those issues.

Based on my knowledge of him from our own two debates, as well as his record as mayor and now presidential candidate, I have three questions about his prospects for 2020:

First, will his ability to carpet-bomb the country with ads be enough to overcome the liabilities of his record in the minds of millions of Democrats? Maybe. That certainly worked in New York City in 2001.

Second, if no candidate wins enough delegates to secure a majority, will Bloomberg have a large enough bloc of convention delegates to influence who the party’s choice of a nominee will be on a second or third ballot? Again, the answer is maybe.

Finally, in the event that Bloomberg secured the nomination, would liberals embrace him if Trump is the alternative? Here, there’s no maybe, even for a Warren supporter like me. After four years of watching Trump try to destroy democracy, the answer is yes.