On the fifth anniversary of the first Tea Party rallies, the movement’s record appears mixed. It swept the GOP to a majority in the U.S. House, where it has blocked President Barack Obama’s most radical ambitions. It helped the GOP win several governorships, launching reforms that broke the unions’ political stranglehold. At the same time, weak Tea Party candidates cost the GOP the Senate, and aggressive legislative tactics cost it support.

The debate for and against the Tea Party obscures the movement’s larger achievement, which is that it reinvigorated a sense of opposition in American politics. Opposition is a natural force in all political systems, to some extent, as Alexis de Tocqueville observed in Democracy in America. Yet it does not have the same formal role in the American system as it does elsewhere, and it has been especially weak–both left and right–in recent years.

The great paradox of the Tea Party is that despite the fact that it currently enjoys the approval of only a minority of Americans, the principles for which it stands are shared by a broad majority. The Tea Party stands for greater freedom and less government, and its flaws all arise from the fact that it has pursued those goals with a far too idealistic expectation that the political system could be restored to those values given enough energy and effort.

It is worth recalling that while the Tea Party was born during the early months of Obama’s presidency, it was conceived during the presidency of George W. Bush–especially during the Wall Street bailouts of the fall of 2008. More broadly, the Tea Party reflected a frustration with government shared by Americans across the political spectrum, a sense that Washington played by its own rules and did not heed the voices of the people.

It was the unique radicalism of the Obama presidency, not his race, that spurred that frustration into action. Obama arose to national prominence by assuming the persona of a unifying personality, but governed in a confrontational style. He ignored the minority party as he introduced massive spending bills and sweeping changes to the role of the federal government in the economy, from the health sector to the energy sector.

The media cast the Tea Party as racist, and that appears to be how Obama understood it as well, as if the new conservative opposition was a reincarnation of the racist Democrats that faced off against Harold Washington, Chicago’s first black mayor, in the 1980s. While the new conservative media, spearheaded by Andrew Breitbart, pushed back against that claim, Obama increasingly lost touch with the reality of the country that elected him.

There is no doubt that the Tea Party class of 2010 failed to live up to its own expectations. It did not balance the federal budget. It did not repeal Obamacare. And crucially, it did not carry its political momentum into the 2012 presidential campaign. One of the most decisive moments in the Tea Party’s history was the failure of the GOP to incorporate it into congressional leadership, which set the state for today’s base-vs.-establishment fight.

And yet the Tea Party’s achievements outweigh its failures. It prevented massive new spending, and bailouts of profligate state governments. It introduced a national debate on entitlement reform, which politicians had been afraid to touch. It also applied the restraint of oversight to a runaway federal bureaucracy. On the state level, it triggered labor reforms that swept the nation and proved fiscal reform was still possible, given political will.

Within the Republican Party itself, the Tea Party brought a new cohort of black, female, and Latino candidates to the fore–leaders who otherwise might not have made it past the party’s gatekeepers. While defending social conservatism, the Tea Party re-oriented the GOP away from the culture war and back towards the defense of individual liberty against the state. It rekindled a cultural interest in the Constitution not seen in decades.

The most significant criticism of the Tea Party is that it has produced some rather weak candidates, whose flaws proved damaging to Republicans across the nation. Two points are worth bearing in mind, however. One is that some of those flawed candidates won anyway. The other is that the establishment’s candidates proved no better–and in many cases, worse–than the neophytes and eccentrics that won GOP primaries with Tea Party support.

Indeed, the success of the Tea Party is astonishing when considered against the massive obstacles it has had to overcome, in addition to resistance from the Republican establishment. The Obama administration launched a campaign of repression against the movement, using the Internal Revenue Service and other means. And the media did all it could to discredit the Tea Party, even blaming it for mass shootings. The movement prevailed.

The truth is that the Republican Party needs the Tea Party movement, both for ideological coherence and grass roots support. And America needs the Tea Party, as well. Without it, the U.S. would be further down the road to insolvency, and our democracy would have long since bowed to Obama’s executive, statist ambitions. The Tea Party has restored loyal opposition to our politics. With the right leadership, it will restore America’s promise.