WASHINGTON — Is the tea party one of the most successful scams in American political history?

Before you dismiss the question, note that word “successful.” Judge the tea party purely on the grounds of effectiveness and you have to admire how a very small group has shaken American political life and seized the microphone offered by the media, including the so-called liberal media.

But it’s equally important to recognize that the tea party constitutes a sliver of opinion on the extreme end of politics receiving attention out of all proportion with its numbers.

Yes, there is a lot of discontent in America. But that discontent is better represented by the moderate voters who expressed quiet disillusionment to President Obama at the CNBC town hall meeting on Monday than by tea party ideologues who proclaim the unconstitutionality of the New Deal and everything since.

The tea party drowns out such voices because it has money — some of it from un-populist corporate sources, as Jane Mayer documented last month in The New Yorker — and has used modest numbers strategically in small states to magnify its impact.

Just recently, tea party victories in Alaska and Delaware Senate primaries shook the nation. In Delaware, Christine O’Donnell received 30,563 votes in the Republican primary, 3,542 votes more than moderate Rep. Mike Castle. In Alaska, Joe Miller won 55,878 votes for a margin of 2,006 over incumbent Sen. Lisa Murkowski, who is now running as a write-in candidate.

Do the math. For weeks now, our national political conversation has been driven by 86,441 voters and a margin of 5,548 votes. A bit of perspective: When John McCain lost in 2008, he received 59.9 million votes.

Earlier this year, much was made of the defeat of Sen. Bob Bennett, a Utah conservative insufficiently conservative for the tea party. Bennett lost not in a primary but at a Republican convention attended by all of 3,500 delegates.

Even in larger states, the tea party’s triumphs were built on small shares of the electorate. Rand Paul received 206,986 votes in Kentucky, where there are more than 1 million registered Republicans and nearly 2.9 million registered voters. Sharron Angle won with 70,452 votes in Nevada, a state with more than 1 million registered voters.

The media have given substantial coverage to tea party rallies and even small demonstrations. But how many people are actually involved in this movement?

Last April, a New York Times/CBS News poll found that 18 percent of Americans identified themselves as supporters of the tea party movement, but slightly less than a fifth of these sympathizers said they had actually attended a tea party rally or meeting. That means just over 3 percent of Americans can be characterized as tea party activists. A more recent poll by Democracy Corps, just before Labor Day, found that 6 percent of voters said they had attended a tea party rally or meeting.

The tea party is not the only small group in history to wield more power than you’d expect from its numbers. In 2008, Barack Obama did very well in party caucuses, which draw many fewer voters than primaries. And it was Lenin who offered the classic definition of a vanguard party as involving “people who make revolutionary activity their profession” in organizations that “must perforce not be very extensive.”

But something is haywire in our media and our politics. Jill Lepore, a Harvard historian whose new book is “The Whites of Their Eyes: The Tea Party’s Revolution and the Battle Over American History,” observed in an interview that there is a “hall of mirrors” effect created by the rise of “niche” opinion media. They magnify small movements into powerhouses while old-fashioned journalism, which is supposed to put such movements in perspective, reacts to the same niche incentives.

There is also the decline of alternative forces in politics. The Republican establishment, such as it is, has long depended far more on big money than on troops in the field. In search of new battalions, GOP leaders stoked the tea party, stood largely mute in the face of its more outrageous untruths about Obama — and now has to defend candidates like O’Donnell and Angle.

And where are the progressives? Sulking is not an alternative to organizing, and weary resignation is the first step toward capitulation. The tea party may be pulling a fast one on the country and the media. But if it has more audacity than everyone else, it will, I am sorry to say, deserve to get away with it.

E.J. Dionne’s e-mail address is ejdionne(at)washpost.com (c) 2010, Washington Post Writers Group This column is licensed to run on TMV in full.