The Washington Post pitches in today to join those hyping the notion that New York Mayor Michael Bloomberg is a viable third-party candidate for president in 2012. The Bloomberg boomlet, such as it is, is mostly the result of the nonstop efforts of the mayor’s staff and the billionaire’s various publication and public relations businesses, such as the Bloomberg Government website. But there have always been enough non-Bloomberg employees attracted by the mayor’s supposed centrism and independence to keep the idea alive.

So what’s the scenario for a Bloomberg candidacy? Of course, it starts and ends with money: Bloomberg has enough money to fund a first-class 50-state presidential run. And as his three mayoral victories demonstrate, he will spend as much money as is necessary.

Another integral element of the scenario is the ideological slot into which Bloomberg can fit. The former member of both the Democratic and Republican parties and his paid flacks have carefully crafted an image of a pragmatist middle-of-the-road technocrat who eschews labels and ideological rigidity. With American politics becoming increasingly polarized and the nation basically split between Red Staters who watch FOX News and Blue Staters who listen to NPR, Bloomberg is supposedly the perfect man to appeal to independents and partisans who are sick of gridlock.

The putative Bloomberg candidacy is helped by the current state of both major parties. The Democrats, led by an unpopular hyper-liberal Barack Obama, have lost the center. At the same time, the Bloomberg boosters are whispering that the Republicans, though on the rebound from their 2008 disaster, have swung too far to the right to appease their conservative base and the Tea Party insurgents to capture the centrists they’ll need to recapture the White House in 2012. And if Sarah Palin is the Republican nominee, they claim the GOP will be doomed. With the nation split between a leftist Obama and a right-wing Palin, a centrist Bloomberg will slip neatly between them and, lubricated by a campaign war chest that could dwarf even the impressive amounts raised in the last cycle by Obama, the mayor will cakewalk to victory, becoming the first ever third-party president.

It’s a neat plan, and if Palin is the GOP standard-bearer and if the economy is still in the doldrums in the summer and fall of 2012, thereby sinking Obama’s hopes, it’s just possible the wealthy mayor could win.

But there is one thing missing from the Bloomberg formula that any candidate, let alone one who expects to win the presidency without the help of a political party, must supply: a rationale for his candidacy. If we look at the history of major independent presidential candidates in the past century — Theodore Roosevelt, Robert LaFollette, Henry Wallace, Strom Thurmond, George Wallace, John Anderson, and Ross Perot — it is clear that the one thing they all had was an issue or set of issues that motivated their followers and voters to buck party loyalties.

The best precedent for Bloomberg might be Ross Perot. In 1992 and 1996, Perot made credible independent runs for the presidency and could have actually won in 1992 had the unstable candidate not imploded under the pressure of the campaign. But Perot’s success was not based solely on the fact that he had the money to pay for his ads. He had an issue: the push for a balanced budget.

But what’s Bloomberg’s issue? There are lots of things he says he is for. As the Post details, he wants a carbon tax, immigration reform, and his attitude toward health care for the elderly seems to be along the lines of those death panels that liberals say are a figment of Sarah Palin’s imagination. But none of those are winners, let alone the sort of thing that will fuel a candidacy. Can he run as a successful businessman who will fix the economy? Maybe. But that alludes to his resume. It is not a cause. Nor can he run on his record in New York, since that will mean explaining the sort of nanny-state intrusions into the lives of citizens — like bans on smoking and trans-fats — that are bound to sink him.

All this leads me to believe that the Bloomberg candidacy is more ego-driven smoke-blowing than anything else. The only rationale for a President Bloomberg is that the billionaire mayor thinks the presidency is the natural next step for a man who conquered the business world and then became the unchallenged king of New York politics. That’s an impressive record, but it is not a reason why Americans will abandon their party loyalties and make him president.