I had to catch a train in Washington last week. The paved street in the traffic circle around Union Station was in such poor condition that I felt as though I was on a roller coaster.

I traveled on the Amtrak Acela, our sorry excuse for a fast train, on which I had so many dropped calls on my cellphone that you'd have thought I was on a remote desert island, not traveling from Washington to New York City. When I got back to Union Station, the escalator in the parking garage was broken.

Maybe you've gotten used to all this and have stopped noticing. I haven't. Our country needs a renewal.

And that is why I still hope New York Mayor Michael Bloomberg will reconsider running for president as an independent candidate, if only to participate in the presidential debates and give our two-party system the shock it needs.

President Obama has significant achievements to his record -- stemming the economic crisis he inherited, managing national security, initiating important reforms from health care to auto mileage standards.

But with Europe in peril, China and America wobbling, the Arab world in turmoil, energy prices spiraling and the climate changing, we are facing some real storms ahead. We need to weatherproof our American house -- and fast -- in order to ensure that America remains a rock of stability for the world. To do that, we'll have to make some big, hard decisions soon -- and to do that successfully will require presidential leadership in the next four years of the highest caliber.

This election has to be about those hard choices, smart investments and shared sacrifices -- how we set our economy on a clear-cut path of near-term, job-growing improvements in infrastructure and education and on a long-term pathway to serious fiscal, tax and entitlement reform. The next president has to have a mandate to do all of this.

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, 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.

Mitt Romney can't do that because of his ludicrous opposition to any tax hikes. Obama, who has a plan to cut, tax and invest -- albeit insufficiently -- could lead, but, for now, he seems preoccupied with some rather uninspiring small ball, preferring proposals like "the Buffett tax" over comprehensive tax reform that would lower all rates, eliminate deductions and raise more revenue.

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 he could change the dynamic of the election and, most important, the course of the next administration, no matter who heads it.

"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."

After his mayoral term is over in 2013, Bloomberg will apparently spend more time running his foundation. That's commendable. But the single greatest act of philanthropy he could do for the country is right now: Run for president as an independent, at least long enough to participate in all the debates.

If he doesn't, and this turns into a presidential race to the bottom, he could donate every dollar he has to fix things in America and they'd be wasted, overwhelmed by our mounting problems.


Thomas Friedman's column is distributed by the New York Times News Service.