THE wave may build even higher as the counting continues, but it has already washed Democrats out the House of Representatives while the Democrats clung onto the Senate. President Obama is certainly the loser, while the Republicans are the nominal victors. But the real winner is the Tea Party, which appeared on no ballots.

Before the mid-term elections, the White House spared no efforts to explain why the tide was running against it. Foreign money, it claimed, was buying votes. As there was no evidence for this charge, it died fast. The next explanation, that the Tea Party was a sinister conspiracy and a front for corporate interests, inevitably struck a chord with leftist true believers, who could not accept the fact that their President's achievements were unpopular with the American people.

The White House's conspiracy-mongering is not surprising, but it is depressing. This country is too big, too diverse, to be deeply swayed by a conspiracy, on the right or the left. President Obama did not win in 2008 because of a left-wing conspiracy: he won because he ran a good campaign, because John McCain ran a mediocre one, and because people were tired of George W. Bush. Rather than indulge in the sickness of inventing conspiracies, it is more helpful to seek to understand why the Tea Party sprang to prominence.

Understanding starts with a fact: the two main political parties in the United States are each over 150-years-old. Common sense would suggest that no political party can survive that long, especially in a country that has changed as much as the United States has, unless it is periodically renewed. That is precisely what has happened.

From the Jacksonians in the 1820s, to the Republicans in the 1850s, to the Goldwater Republicans in the 1960s, populist movements have periodically refreshed American politics. In the end, they have, by and large, been absorbed into an existing party: only Lincoln's Republicans founded a new one.

Europeans are suspicious of populist movements because populists in Europe tend to be racists, fascists, or communists. But the US has classical liberalism in its bones. In the United States, popular movements usually seek not to depart from the truths on which this nation was founded, but to return to them.

From this perspective, the challenge for the Tea Party is to endure – none of the populist movements won quick success at the highest level Indeed, every one of them lost the presidential race the first time round. 2010 is only the beginning, and if history is any guide, the struggle will not end in 2012. Of course, patterns are made to be broken, but that pattern suggests that President Obama will not be easy to beat.

Nevertheless, President Obama was himself a product of a popular wave, one that now appears to have receded. The American people were angry in 2006 and 2008 at the Republicans, and now they are angry at the Democrats.

This run of angry elections reveals the second way to think about the Tea Party: it is the product of a political system that has persistently failed to give the people what they want.

The lesson the Democrats took away from George W Bush was that the nation wanted more liberalism. Their sudden collapse implies that lesson was incorrect. There is a strong case for arguing that, far from being too conservative, George W Bush was too liberal.

At home, he was a small taxer, but a big spender. Abroad, his policies were often described as Wilsonian – and Woodrow Wilson was the quintessential American liberal. From this perspective, the challenge to the Tea Party will be to remain true to the conservative principles that brought it success.

The worst mistake the newly-triumphant Republicans could make is to believe that this election was a tea-fuelled rejection of President Obama that has rallied the people to their side. Another way to think about the Tea Party is that it is not just about the current occupant of the White House.

True, every election is a referendum on the government. But while Republicans have done well, the Republican brand remains unpopular. Indeed, the Tea Party was as much a revolt against the establishment Republican Party as it was against the Democrats. Finally, when the politics are over and the governing begins, there is a simple fact to be faced: the US is spending too much money. Outrage at that, in all its forms, is what created the Tea Party.

The fourth and final way to think about the Tea Party is that it is the start – the overdue start – of a generational protest against the fact that today's children will be called upon to pay for their parents' retirement, against the belief that prosperity can be built on ever-higher piles of government debt, and against the belief that we must settle for the end of the American Dream.

Today, the Tea Party's voters have put Republican candidates on the verge of government. Tomorrow, they must begin to live up to that responsibility.

Ted R Bromund is a Senior Research Fellow at the The Margaret Thatcher Center for Freedom at The Heritage Foundation.