Because his views on gun control, abortion and climate change fit squarely in the Democratic mainstream without being obnoxious or frightening to middle-of-the-road America. The Democratic base will not sit out the election and squander its chances to oust Trump just because Bloomberg’s wealth offends them or because they won’t vote for a candidate who doesn’t embrace the Green New Deal.

Because even his opponents know there can be no gainsaying his ability to serve as president; or his talent for appointing competent deputies; or his mastery of the mechanics of government; or his overwhelmingly successful tenure as New York mayor; or his understanding of business and the economy; or his immediate credibility on the world stage; or his sobriety of judgment or general probity of character. Mike Bloomberg has donated more money — at least $6 billion — than Donald Trump has ever had.

Because the voters who will matter in the election — that is, those who live neither in deep blue nor deep red states — want a centrist. Democrats in Michigan, Wisconsin, Pennsylvania, North Carolina, Arizona and Florida tell pollsters they want “a Democratic nominee who is more moderate than most Democrats,” and that they prefer “one who would bridge the partisan divide,” according to a report Friday from my colleagues Jonathan Martin and Katie Glueck.