But, today, neither party is generating that mandate — talking seriously enough about the taxes that will have to be raised or the entitlement spending that will have to be cut to put us on sustainable footing, let alone offering an inspired vision of American renewal that might motivate such sacrifice. That’s why I still believe that the national debate would benefit from the entrance of a substantial independent candidate — like the straight-talking, socially moderate and fiscally conservative Bloomberg — who could challenge, and maybe even improve, both major-party presidential candidates by speaking honestly about what is needed to restore the foundations of America’s global leadership before we implode…

Bloomberg doesn’t have to win to succeed — or even stay in the race to the very end. Simply by running, participating in the debates and doing respectably in the polls — 15 to 20 percent — he could change the dynamic of the election and, most importantly, the course of the next administration, no matter who heads it. By running on important issues and offering sensible programs for addressing them — and showing that he had the support of the growing number of Americans who describe themselves as independents — he would compel the two candidates to gravitate toward some of his positions as Election Day neared. And, by taking part in the televised debates, he could impose a dose of reality on the election that would otherwise be missing. Congress would have to take note.

“The right kind of independent candidate would explain that the real question on taxes, once the economy is back on track, is this: Given that taxes have to rise, how should we raise the revenue we need in ways that are best for the economy?” wrote the columnist Matt Miller in The Washington Post last week. “The answer would involve lower taxes on payrolls and corporate income, and higher taxes on dirty energy and consumption.”