Correction: An earlier version of this post incorrectly stated that Tom Steyer had stopped funding his Need to Impeach ad campaign. This version has been updated.

Former New York mayor Mike Bloomberg finally entered the Democratic presidential race on Sunday. To make up for lost time, reports The Post, “his campaign has made more than $30 million in television advertising reservations to help introduce him as a candidate. … Bloomberg has also announced a $100 million ad campaign to criticize Trump in key battleground states and a $15 million voter registration effort in those same places.” That’s an enormous sum — and a colossal waste compared to how else he could spend it.

It’s hard to overstate the size of the mountain the Bloomberg 2020 train is trying to climb. Political history is littered with late entrants who fell well short; you have to go back to Robert F. Kennedy in 1968 to find a tardy candidacy that met with sustained success. Bloomberg’s plan to largely skip the early primary contests is particularly bold given that no Democrat has won the nomination without winning delegates in Iowa or New Hampshire. His favorability numbers among Democrats are worst-in-the-field, likely thanks to his past support for controversial policies such as “stop and frisk.” And even if he does somehow win the nomination, there’s little polling evidence that he’d be a stronger general election candidate than other Democrats.

Smarter targets for the billionaire’s largesse abound. Bloomberg could, for example, reprise his 2018 political spending, when he spent $41 million on House races and $112 million overall. After all, the former mayor’s own team touted his money’s effectiveness in a New York Times feature, with even outside experts agreeing that the spending probably gained Democrats several House seats. And with 2020 a far more favorable Senate map for Democrats, tens of millions from Bloomberg could go a long way toward flipping the upper chamber.

Or Bloomberg could jump into state-level races again. As with Congress, Bloomberg is well aware of his spending power at the state level: This year, he spent $2.5 million for pro-gun control candidates in Virginia’s state legislature elections, which ended with Democrats in total control of the state government for the first time in 26 years. In contests where campaign expenditures are usually in the tens or hundreds of thousands, $30 million — let alone $100 million — spread across several states would be a game-changer.

Or Bloomberg could spend his millions to back specific causes, as he has in the past with gun control. For example, if he supports impeaching the president, Bloomberg could specifically back vulnerable House incumbents who are facing anti-impeachment ad blitzes. Here Bloomberg has a partner in waste in California billionaire Tom Steyer, who still funds his Need to Impeach ad campaign but is spending much more on his run in the Democratic race — just as pro-impeachment ads are most sorely needed. As The Post’s David Weigel notes, “It’s an O. Henry level irony that some Democrats are getting queasy about anti-impeachment TV ads in their districts, and the billionaire who had been running air cover on impeachment is, instead, running for president.” Instead, Steyer is setting money on fire in support of ideas such as term limits for members of Congress, which both are unconstitutional and boost lobbyist influence.

Let’s be clear: That any American can exert this much political influence with his or her personal fortune is fundamentally undemocratic. But so long as the Supreme Court’s conservative majority preserves the fiction that money is speech, the least we can ask is that those Americans fortunate enough to wield such power do so wisely for good causes. Any of the three causes — Congress, impeachment or state legislatures — would likely have a better return on investment than a long-shot presidential bid. Instead, Bloomberg looks set to spend on his own ego.

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