MOSCOW – What a difference a plunging ruble makes. A few short days ago, Russian President Vladimir Putin was a strategic genius, outplaying Western leaders everywhere – in the Middle East, in China, and especially in Ukraine. Today, he’s the destroyer of his country and his political life could be in jeopardy.

I’ve long thought that he has pursued a pre-World War Two course which could only end badly – a course in which his power is maximized by crushing internal opponents, expanding empire and using the military to frighten neighboring countries into submission. It’s true that all nations seek advantage, sometimes ruthlessly, but in the West, a politics has evolved which generally seeks win-win outcomes and avoids zero-sum confrontations. That usually means tacitly accepting U.S. hegemony and U.S.-sustained international rules of the game, and to that, Putin cannot reconcile himself.

Putin has increasingly developed a contempt for a Europe which has no central power, no centrally-controlled military force and a lingering economic crisis. He measures himself, as did the Soviet Union, against the United States; he has no kind of relationship with President Barack Obama, but he does recognize, and resent, the power of the United States. His actions this past year in Ukraine have been a calculated defiance of the American-sponsored international order – pulled off, apparently, with panache (and thousands of casualties in the former Soviet republic).

This assumption of co-equal status now dissolves. On Monday night, the Russian Central Bank hiked interest rates to 17 percent in a failed effort to stop the free-fall of the ruble, which is down 56 percent against the dollar this year. It has been on a rollercoaster ride since – up 9 percent early Tuesday but down 17 percent by nightfall, hitting 100 to the euro. On Wednesday, it gained slightly again — just as Apple ceased to sell its products in Russia, citing the monetary turbulence. On Thursday, the president did a 3-hour press conference in which he generously allowed anyone to call the last few days a crisis if they wished, but he wouldn’t join them.

And so the high political talk in Moscow — some of which I’ve been privy to over the past few days — is not of the need for Russian Central Bank Governor Elvira Nabiullina to go (though she may); but of something much more fundamental. The talk is of the need for major policy change; or, more radically, regime change.

The argument for both is the same. The bloodless taking of Crimea from Ukraine earlier this year, and support for the pro-Russian separatists in the eastern Donbass region, gave Putin the glow of a national hero. But now, Russia is suffering, and will suffer more, from the fall in oil prices and the effect of Western sanctions. Putin could not avoid the oil price fall, but he brought on the sanctions. His geopolitical victories of the past year now look like dangerous, and irresponsible, strutting.

He’s in charge; he takes the blame. What can he do? He might attempt to tough it out. The ruble may steady. Oil prices may rise again, even if not soon. The country’s reserves are still large — and even if it is bleeding cash, those reserves should be a cushion deep into 2015. Some analyses see the Western reaction to this as overheated, as wishful Western thinking that Russia is going down.

Politically, he has no obvious challenger; the demonstrations of three years ago have not been repeated; the polls, till now, show continued support. Masha Lipman, a top analyst of the Russian political scene, says that the liberal camp, so active in the protest movements of 2011-12, has shrunk to a hard core with little popular appeal. There are also signs that the rhetoric on Ukraine is changing. Both Prime Minister Dmitry Medvedev and Foreign Minister Sergei Lavrov have called for an agreement to keep the eastern Donbass region in Ukraine, which may placate Europe and Washington.

Putin has another problem. The men around him and in the fractious circles of Russian power are losing too much and are itching for change. The challenge to a tough-it-out course will come from within and resistance could spark a bare-knuckle fight over the legitimacy of Putin’s wealth, and that of his closest allies, that could become ugly.

One option for the Russian president is to bring in a stronger figure than the obedient Medvedev to the prime minister’s office. The most radical choice would be Alexei Kudrin, post-Soviet Russia’s longest serving Finance Minister (2000-2011). His economic and social liberalism would be at least an implicit criticism of Putin’s reactionary rhetoric. Many believe he is the only political figure who can contradict the President and retain his respect. Last month, he told a Reuters conference in Moscow that the Ukraine adventure, and the retaliatory sanctions — strengthened this week by the U.S. Congress –— were badly weakening the economy and must be addressed.

There are more conservative choices, who may be more amenable to a president who likes a strong state and capitalists too weak to be independent of him. Conservatives like Igor Sechin, a former deputy prime minister who is now executive chairman of Rosneft, Russia’s oil giant. He’s said to have a secret service past. Unlike the president’s, it was unofficial. He has efficiently integrated into Rosneft the large assets held by Menatep, the oil company which had belonged to the jailed Mikhail Khodorkovsky. He is a full member of the Siloviki, the former intelligence officers whom Putin instinctively promotes and protects. The drubbing given to the price of his product has taught a hard lesson in the workings of the globalized economy: but where Kudrin wants to reshape Russia so that it can better cope with that, Sechin is more likely to seek protection from it through state ownership and controls.

Putin has very little time. The long good stretch of Russian growth and geopolitical strut is over, and a nerve-grinding period of adjustment and appeals for belt tightening and patience is the best he can hope for. The worst is a bitter internal struggle over a financial abyss – a nightmare for Russia, for Europe and the world.

PHOTO: Russian President Vladimir Putin is seen on a screen during his annual end-of-year news conference in Moscow, Dec. 18, 2014. REUTERS/Maxim Zmeyev