That which can’t continue doesn’t. A nation can spend and spend, pile debt upon debt, but eventually there comes a reality moment when some leader emerges to say enough is enough and when decent people, looking around at themselves and their own best nature, respond by demanding a return to responsibility.

In the United States, we’re not at that moment yet. Private debt is being replaced by public debt. New entitlements are being created, and the money that could be used to ward off fiscal disaster is being used for other things. Here, Democrats still get ahead by promising tax cuts for the bottom 98 percent and Republicans get ahead by promising tax cuts for all and Medicare cuts for none.

But Britain has hit its reality moment. The Brits are ahead of us when it comes to public indebtedness and national irresponsibility. Spending has been out of control for longer and in a more sustained way.

But in that country, the climate of opinion has turned. There, voters are ready for a politician willing to face reality. And George Osborne, who would become the chancellor of the Exchequer in the likely event that his Conservative Party wins the next election, has aggressively seized the moment.

In a party conference address earlier this month, Osborne gave the speech that an American politician will someday have to give. He said that he is not ideologically hostile to government. “Millions of Britons depend on public services and cannot opt out,” he declared. He defended government workers against those who would deride them as self-serving bureaucrats: “Conservatives should never use lazy rhetoric that belittles those who are employed by the government.”

But, he pivoted, “it is because we treat those who work in our public sector with respect that I want to be straight with you about the choices we face.” The British government needs to cut back.

Osborne declared that his government would raise the retirement age. That age was scheduled to rise at some point in the distant future. Osborne vowed to increase it sometime in the next five to 10 years.

Osborne declared that there would be no tax cuts any time soon. He said that as a matter of principle he believes that the top income tax rate of 50 percent is too high. But, he continued, “we cannot even think of abolishing the 50 percent rate in the rich” while others down the income scale are asked to scrimp.

Osborne offered government workers the same sort of choice that many private sector executives are forced to make. He proposed a public sector pay freeze in order to avoid 100,000 layoffs. He said that the pay freeze would apply to all workers except those making less than £18,000 (nearly $29,000) “because I don’t believe in balancing the budget on the backs of the poorest. Nor do you.”

There were other austerities. Osborne vowed to cut a program he once supported but which has not proved its worth: a baby bond program that was meant to help offset the costs of childhood. There would no longer be means-tested tax credits for families making more than £50,000.

Osborne’s speech was not an isolated event. The Conservatives have treated British voters as adults for a year now, with a string of serious economic positions. The Conservatives supported the Labour government bank bailout, even though it was against their political interest to do so. Last November, Osborne opposed a cut in the value-added taxes on the grounds that the cuts were unaffordable and would not produce growth. It is not easy for any conservative party to oppose tax cuts, but this one did it.

And the public has responded. The Conservatives now have a dominating lead over Labour. Over all, support for the Conservatives rose by 4 percentage points after Osborne’s speech. The polls reveal that nearly 60 percent of Britons support the austerity measures. The Conservatives have a 21-point lead when it comes to being honest about public finances and a 14-point lead on economic policy generally.

The key is that Osborne is not merely offering pain, but a different economic vision — different from Labour and different from the Thatcherism that was designed to meet the problems of the 1980s.

In the U.S., the economic crisis has caused many to question capitalism. But Britain has discredited the center-left agenda with its unrelenting public spending, its public development agencies and disappointing public-private investment partnerships.

Osborne and David Cameron, the party leader, argue that Labour’s decision to centralize power has undermined personal and social responsibility. They are offering a responsibility agenda from top to bottom. Decentralize power so local elected bodies have responsibility. Structure social support to encourage responsible behavior and responsible spending.

If any Republican is looking for a way forward, start by doing what they’re doing across the Atlantic.