Will he, or won’t he?

That is, will Michael Bloomberg decide on an Independent run for the presidency, will Democrats tap him, or will he stay home? A decision must be made reasonably soon, if he wants to get on the ballot in all 50 states.

A couple of weeks ago the New York Times published a front page article, “Bloomberg, Sensing an Opening, Revisits a Potential White House Run.” They noted he had tasked his advisors with determining the merits of an Independent candidacy.

Mr. Bloomberg, a three-term mayor of the city of New York, is said to be motivated by the possibility — remote as it may seem — of voters having a Hobson’s choice in November: Bernie Sanders or Donald Trump. Mrs. Clinton assured him there was no reason for him to harness up.

She would be the Democrat nominee. Republicans remained silent.

They know that an Independent run by Mr. Bloomberg would do more harm to the Democrat contender than the Republican. Mr. Bloomberg ran for mayor as a Republican and is now an Independent. But he had been a lifelong Democrat. It is where his sympathies lie.

History is replete with third parties, from the anti-Masonics and Free Soilers during the first half of the 19th Century to the American Independent and Reform parties in the second half of the 20th Century. In 1860, Abraham Lincoln was the first man to run for president as a Republican, effectively making him a third-party candidate.

He won against three others, garnering 39.6 percent of the popular vote. But apart from Lincoln, over the past 150 years no third-party candidate has ever won 30 percent of the popular vote.

Theodore Roosevelt, as the Bull Moose candidate in 1912, came closest, garnering 27.4 percent. Eighty years later, Ross Perot received 19 percent when he ran on the Reform Party in 1992, but he received no Electoral College votes. Third-party candidates Robert LaFollette got 16 percent in 1924 and George Wallace, 10 percent in 1968.

Third-party candidates have been, however, spoilers. In 1912, Roosevelt’s entry cost William Howard Taft re-election. In 1924, Calvin Coolidge won, in part, because LaFollette’s candidacy took votes from John Davis. In 1968, George Wallace siphoned off Southern Democrats and Hubert Humphrey lost to Nixon. And, almost certainly, Ross Perot’s run in 1992 cost George H.W. Bush re-election.

Mayor Bloomberg may face one other historical impediment: No modern mayor of New York City has gone on to higher office.

Nevertheless, the presidency of the United States — the most powerful position on earth — is a big prize. The prospect for historical immortality is seductive.

Mr. Bloomberg has a good-sized ego and is worth north of $30 billion. And, perhaps most important, his political philosophy — apart from a preference for “nannyism” — tends to be centrist.

His ties to Wall Street would provide fodder to negative populist rhetoric, but he is a self-made man, a “doer” with vision. He may think this is his time.

At the age of 73 — he will be 74 next week — this would be his only shot. Ronald Reagan, at 69, was the oldest man ever elected president, and he was five years younger than Michael Bloomberg would be.

There are, in my opinion, flawed candidates in both parties, beyond Sen. Sanders and Mr. Trump. Mrs. Clinton comes to mind, with her deliberate decision to store her State Department emails on a private server, her lies regarding Benghazi and myriad scandals reaching back into the 1980s.

Ted Cruz is not deemed collegiate by his congressional colleagues. It says something about his character that not one of his senatorial brethren have endorsed him.

Being able to get along is a lesson Americans should have learned from the incumbent. Democrats have a limited menu off of which to choose. But Republicans have viable alternatives: Governors Jeb Bush, John Kasich and Chris Christie are experienced and competent.

While faults can be found in all of them, I would be happy with any. My favorite, however, is Sen. Marco Rubio. His youth is countered by sensible judgment and good character. He is energetic, smart, and liked and admired by is colleagues — and he is the Republican candidate most feared by Democrats.

Democrats, on the other hand, could be in a tough spot. Most do not want a 74-year-old Socialist and there is risk — perhaps low — that Mrs. Clinton could be indicted. While Democrats work hard to portray inclusiveness, in fact they have a shallow bench.

The age of their candidates — now that O’Malley is out of the race — including potential ones, suggest a party more comfortable with the past than the future. The Obamas and the Clintons are not close, but if Mrs. Clinton becomes the standard bearer, the president will stick with her. But if her legal problems worsen, Mr. Obama may look elsewhere.

Joe Biden and Elizabeth Warren are obvious possibilities, but both have imperfections. Mr. Biden is older, without the freshness of Bernie Sanders. Mr. Obama could turn to his kindred spirit, Elizabeth Warren, but he may want a more attractive alternative. Ms. Warren has lied about her past in order to advance her career. If you recall, she claimed to be of Cherokee heritage. (See the piece I wrote on November 9, 2012, “Pocahontas Goes to Washington.”1) She is also on the extreme fringe of the Left. As well, she is not young. She will be 67 in June – old enough (but not wise enough) to be Marco Rubio’s mother.

Mr. Obama is determined that his legacy not be at risk, which could happen should Republicans gain the White House and keep the Senate and the House. The inevitability of Hillary’s coronation now seems not so inevitable.

President Obama has kept his options open. He has not said whom he would support. This is where Michael Bloomberg could step in. Keep in mind, Mr. Bloomberg had been a life-long Democrat before running for Mayor in 2001 as a Republican.

That year the Democrat field was crowded with aspirants wanting to succeed Rudy Giuliani. Michael Bloomberg, always a pragmatist, correctly thought it would be easier to win the nomination against former Congressman Herman Badillo, then a 62-year-old former Congressman, than to compete for the Democrat nomination against a field of a half dozen. In 2005, after winning re-election, he switched his registration to Independent.

Perhaps it is only wishful thinking, but my guess is that Republicans, in the end, will nominate a candidate with broad appeal, an individual who exudes optimism, and whose policies will give business the confidence to invest in the future and give people the confidence that, with the right education and incentives, they can create their own destinies. A person who recognizes that government is necessary, but should always be subordinate to the rights of individuals.

There is no one on the Democrat slate who can do that. Mr. Sanders’ beliefs imply a state that supersedes the individual. Mrs. Clinton has abandoned the more centrist views of her ethically challenged husband for the more radical views espoused by Mr. Obama and Mr. Sanders.

If Democrats hope to keep the White House, they will have to find someone with broader appeal. Michael Bloomberg might be that person.

Perhaps it is already too late, but if I were a member of the Democratic National Committee, I would be nervous regarding my prospects, especially if Mr. Rubio is nominated. I would look upon Mr. Bloomberg as a possible savior. As a competitor he would be formidable, but not necessarily unbeatable by the right Republican.

His “nannyism,” for example, is troubling. But he would be an attractive candidate, with generally centrist views. It is curious that the possibility has received so little attention.