NEWS FLASH: The next president of the United States, like the last 29, will be a Republican or a Democrat.

That’s not news, you say? But surely it must be. Haven’t we been hearing for months from accomplished and influential people — people like former Disney CEO Michael Eisner, private-equity investor Peter Ackerman, and former New Jersey Governor Christie Whitman — that the post-partisan hour was finally at hand? Weren’t legions of Americans said to be ready to turn their backs on the old two-party system, with all its divisiveness and ideological rigidity? Haven’t tens of millions of dollars been donated to Americans Elect, the widely praised anti-special-interest reform group intent on anointing a genuinely bipartisan ticket — a presidential candidate from one party and a vice-presidential running mate from the other — and setting up a three-way race for the White House in November?

All quite true. And all quite irrelevant. Americans Elect has plenty of money, an elegant web presence, and such organizational savvy that as of last week it had qualified for the November ballot in 29 states, including California, Michigan, and Ohio. But it is not going to break, or even shake, the Republican-Democratic lock on the White House.

Dismay over the American two-party system is nothing new. It’s so old, in fact, that it predates the federal constitution. “There is nothing I dread so much as a division of the Republic into two great parties, each arranged under its leader and converting measures in opposition to each other,” wrote John Adams in 1780. His great rival Thomas Jefferson agreed: “If I could not go to heaven but with a political party, I would not go there at all.” Yet all their anti-partisan pieties didn’t keep Adams and Jefferson from competing vigorously against each other as nominees of the first two American political parties, the Federalists and the Democratic-Republicans.

More than 225 years later, Americans by the millions follow the Adams/Jefferson pattern, lamenting partisanship in the abstract while sustaining it in practice.

In recent Gallup polls, more than half of respondents say the Republican and Democratic parties do such a poor job that the nation needs a third party. In an ABC News/Washington Post poll last November, voters by a 2-1 ratio responded favorably to the idea of an independent running for president against the major-party nominees. More than a few high-minded elites were certain the moment was ripe for a powerful centrist challenge to the long supremacy of Rs and Ds. “What Amazon.com did to books, what the blogosphere did to newspapers, [and] what the iPod did to music,” gushed The New York Times’s Thomas Friedman, “Americans Elect plans to do to the two-party duopoly that has dominated American political life — remove the barriers to real competition, flatten the incumbents, and let the people in.”

But Americans Elect crashed and burned last week. Its much-hyped online primary process, touted as a way for any registered voter to take part in choosing a presidential ticket, achieved nothing. To survive the primary’s first round, a candidate needed at least 10,000 clicks of support — hardly an insuperable bar in an organization that claims to have signed up more than 400,000 members. Yet no declared candidate came close. Former Louisiana Governor Buddy Roemer, the Americans Elect frontrunner, managed to attract just 6,281 supporters. (Boston University economist Laurence Kotlikoff finished fourth, with 2,023.)

Chalk up another win for that “two-party duopoly.”

Americans may claim they long for an alternative. Pundits tell them that the parties have never been more polarized, that gridlock has reached crisis levels, and that the nation desperately requires politicians more interested in solving problems than in winning elections.

Yet the two-party system remains deeply rooted in our political life, and for good reason. The broad struggle between Republicans and Democrats reflects, however messily, the ancient tension between America’s two profoundest political goals – liberty and equality. Ideological purists can lament that there isn’t a dime’s worth of difference between the two parties, and for those who feel that way, there are always alternatives. Segregationist George Wallace, deficit hawk Ross Perot, Socialist Norman Thomas, Libertarian Ron Paul, consumerist scourge Ralph Nader – all ran for president on third-party lines, and all attracted some passionate supporters (and in Wallace’s case, even some electoral-college votes) along the way.

None, however, made any lasting change in America’s political landscape. For the vast majority of voters, political competition still comes down to Republicans vs. Democrats. Just as well: For a nation so profoundly divided, two parties are enough.

(Jeff Jacoby is a columnist for The Boston Globe. His website is www.JeffJacoby.com).