One of the strengths of the American system has been its remarkable ability to adapt to changing circumstances. When things aren’t working, leaders lead, followers follow and we change them, incrementally if possible, boldly if not. If the new thing doesn’t work, we fix it or try something else until we get it right.

If our country is now in decline — and there is some evidence of that — it is not because of China or because government is too big or because of some inevitability surrounding the rise and fall of great powers. It is because our political system has become so dysfunctional that this adaptability quickly is eroding.

Let’s start with leadership. Haley Barbour, Mike Huckabee and Mitch Daniels have the intelligence, knowledge, political sophistication and success at governing to qualify them as serious presidential candidates. That all three have taken themselves out of the running for 2012 speaks not only to the stranglehold that special interests and ideological extremists have over the party primaries and caucuses, but also to a campaign process that has become so grueling and distasteful that only charlatans and egomaniacs are willing to put themselves through it.

Fickle voters, of course, deserve a good part of the blame for this leadership vacuum. Whatever you think of President Obama’s agenda during the past two years, it was pretty much what he had promised. Two years on, his reward was a new Republican majority determined to reverse and delegitimize everything he had done. Now six months after that, the public has decided it doesn’t like the Republican program any better.

The air of unreality that now permeates the political discussion is truly mind-boggling.

I wonder how many more natural disasters it will take, or how much more data about rising temperatures and falling crop yields, or how many maps showing the melting of the polar ice caps, before we can pick up again with a serious conversation about what to do about global warming.

How much more of the nation’s wealth will have to be transferred to senior citizens with six-figure incomes before it will be politically acceptable to hold their future Social Security benefit increases to the rate of inflation?

Does anyone seriously believe you can’t cut 15 percent from weapons spending at the Pentagon, or 15 percent from the least-effective programs at the departments of Commerce, Labor, Education and Homeland Security, without endangering the national defense or the economy?

How much bigger would the federal government debt have to get before the industrial country with the lowest tax burden might decide to raise taxes on the 10 percent of households that earn half of the nation’s income?

Can anyone watch the instant replay from the recent financial crisis — the new movie of Andrew Ross Sorkin’s “Too Big to Fail” — and come away thinking that the real problem in this country is that government has put too tight a leash on Wall Street and the banks?

Do federal workers expect that they can continue to receive pensions and health benefits nearly double those of the average private-sector employee?

Is anyone so gullible that they think oil companies raking in record profits from the windfall of $100-a-barrel will stop drilling if they lose a few of their tax loopholes?

Does anyone watching what’s happening to Greece, Ireland and Portugal seriously believe that, as the tea partiers assert, that there will be no lasting consequences to a U.S. government default?

So much of the policy debate now occurs outside the hash marks of political and economic reality that there can be no constructive debate. How can you have a conversation with someone who looks up and says the sky is green?

Apparently the White House view is that the president can win reelection by letting this craziness continue unchallenged, even if it means accomplishing little over the next 16 months. Maybe so. But in the process, his party is likely to lose control of the Senate while falling short of winning back the House. He’ll find himself with a weak mandate and no way to implement it, with congressional leaders of both parties no more willing to accept reality than they are now.

The better strategy is for the president to forget about trying to broker deals between congressional leaders who have no instinct for compromise and put forward his own bold program — not the liberal fantasy he and his party might prefer, but practical, centrist compromises the country will actually accept: A 10-year budget-balancing plan that mixes spending cuts and tax increases. Market-based compensation for federal workers. Cost-saving reforms to Medicare and Social Security. A big push on trade, exports and worker training. An energy tax to reduce carbon emissions, rebated annually to taxpayers. More drilling for oil and gas in exchange for tighter regulation and higher royalties. Elimination of hundreds of low-performing government programs. A big new infrastructure bank. Tougher regulation of Wall Street, and lighter regulation on Main Street.

The aim wouldn’t be to get any of it through the current do-nothing Congress, but to create a mandate for the next Congress and the next administration. By demonstrating his willingness to take on the ideologues, the special interests and the cable bullyboys of both the left and the right, Obama would liberate himself and the country from the political rut we’re all in. And in the process he could finally make good on what was always the central promise of his presidency: to change the way business is done in Washington.