This fact marks our political age: The pendulum is swinging faster and in shorter arcs than it ever has in our lifetimes. Few foresaw the earthquake of 2008 in 2006. No board-certified political professional predicted, on Election Day 2008, what happened in 2009-10 (New Jersey, Virginia and Massachusetts) and has been happening, and will happen, since then. It all moves so quickly now, it all turns on a dime.

But at this moment we are witnessing a shift that will likely have some enduring political impact. Another way of saying that: The past few years, a lot of people in politics have wondered about the possibility of a third party. Would it be possible to organize one? While they were wondering, a virtual third party was being born. And nobody organized it.

Here is Jonathan Rauch in National Journal on the tea party's innovative, broad-based network: "In the expansive dominion of the Tea Party Patriots, which extends to thousands of local groups and literally countless activists," there is no chain of command, no hierarchy. Individuals "move the movement." Popular issues gain traction and are emphasized, unpopular ones die. "In American politics, radical decentralization has never been tried on such a large scale."

Here are pollsters Scott Rasmussen and Doug Schoen in the Washington Examiner: "The Tea Party has become one of the most powerful and extraordinary movements in American political history." "It is as popular as both the Democratic and Republican parties." "Over half of the electorate now say they favor the Tea Party movement, around 35 percent say they support the movement, 20 to 25 percent self-identify as members of the movement."

So far, the tea party is not a wing of the GOP but a critique of it. This was demonstrated in spectacular fashion when GOP operatives dismissed tea party-backed Christine O'Donnell in Delaware. The Republican establishment is "the reason we even have the Tea Party movement," shot back columnist and tea party enthusiast Andrea Tantaros in the New York Daily News. It was the Bush administration that "ran up deficits" and gave us "open borders" and "Medicare Part D and busted budgets."

Everyone has an explanation for the tea party that is actually not an explanation but a description. They're "angry." They're "antiestablishment," "populist," "anti-elite." All to varying degrees true. But as a network television executive said this week, "They should be fed up. Our institutions have failed."

Barbara Kelley

I see two central reasons for the tea party's rise. The first is the yardstick, and the second is the clock. First, the yardstick. Imagine that over at the 36-inch end you've got pure liberal thinking—more and larger government programs, a bigger government that costs more in the many ways that cost can be calculated. Over at the other end you've got conservative thinking—a government that is growing smaller and less demanding and is less expensive. You assume that when the two major parties are negotiating bills in Washington, they sort of lay down the yardstick and begin negotiations at the 18-inch line. Each party pulls in the direction it wants, and the dominant party moves the government a few inches in their direction.

But if you look at the past half century or so you have to think: How come even when Republicans are in charge, even when they're dominant, government has always gotten larger and more expensive? It's always grown! It's as if something inexorable in our political reality—with those who think in liberal terms dominating the establishment, the media, the academy—has always tilted the starting point in negotiations away from 18 inches, and always toward liberalism, toward the 36-inch point.

Democrats on the Hill or in the White House try to pull it up to 30, Republicans try to pull it back to 25. A deal is struck at 28. Washington Republicans call it victory: "Hey, it coulda been 29!" But regular conservative-minded or Republican voters see yet another loss. They could live with 18. They'd like eight. Instead it's 28.

For conservatives on the ground, it has often felt as if Democrats (and moderate Republicans) were always saying, "We should spend a trillion dollars," and the Republican Party would respond, "No, too costly. How about $700 billion?" Conservatives on the ground are thinking, "How about nothing? How about we don't spend more money but finally start cutting."

What they want is representatives who'll begin the negotiations at 18 inches and tug the final bill toward five inches. And they believe tea party candidates will do that.

The second thing is the clock. Here is a great virtue of the tea party: They know what time it is. It's getting late. If we don't get the size and cost of government in line now, we won't be able to. We're teetering on the brink of some vast, dark new world—states and cities on the brink of bankruptcy, the federal government too. The issue isn't "big spending" anymore. It's ruinous spending that they fear will end America as we know it, as they promised it to their children.

So there's a sense that dramatic action is needed, and a sense of profound urgency. Add drama to urgency and you get the victory of a tea party-backed candidate.

That is the context. Local tea parties seem—so far—not to be falling in love with the particular talents or background of their candidates. It's more detached than that. They don't say their candidates will be reflective, skilled in negotiations, a great senator, a Paul Douglas or Pat Moynihan or a sturdy Scoop Jackson. These qualities are not what they think are urgently needed. What they want is someone who will walk in, put her foot on the conservative end of the yardstick, and make everything slip down in that direction.

Nobody knows how all this will play out, but we are seeing something big—something homegrown, broad-based and independent. In part it is a rising up of those who truly believe America is imperiled and truly mean to save her. The dangers, both present and potential, are obvious.

A movement like this can help a nation by acting as a corrective, or it can descend into a corrosive populism that celebrates unknowingness as authenticity, that confuses showiness with seriousness and vulgarity with true conviction. Parts could become swept by a desire just to tear down, to destroy.

But establishments exist for a reason. It is true that the party establishment is compromised, and by many things, but one of them is experience. They've lived through a lot, seen a lot, know the national terrain. They know how things work. They know the history. I wonder if tea party members know how fragile are the institutions that help keep the country together.

One difference so far between the tea party and the great wave of conservatives that elected Ronald Reagan in 1980 is the latter was a true coalition—not only North and South, East and West but right-wingers, intellectuals who were former leftists, and former Democrats. When they won presidential landslides in 1980, '84 and '88, they brought the center with them. That in the end is how you win. Will the center join arms and work with the tea party? That's a great question of 2012.