Among those likely to be on Monday’s list, officials said, are Igor Sechin, president of the Rosneft state oil company, and Aleksei Miller, head of the Gazprom state energy giant.

“It’s like standing in a circle and all of a sudden everyone in the circle is getting a bomb thrown on them, and you get the message that it’s getting close,” said Senator Robert Menendez, Democrat of New Jersey, the chairman of the Foreign Relations Committee, describing at a recent hearing the way the sanctions are getting closer to Mr. Putin.

Putin’s Denials

Mr. Putin’s reported income for 2013 was just $102,000, according to a Kremlin statement this month. Over the years, he has crudely dismissed suggestions of personal wealth. “I have seen some papers about this,” he said at a news conference in 2008. “Just gossip that’s not worth discussing. It’s simply rubbish. They picked everything out of someone’s nose and smeared it on their little papers.”

How much Mr. Putin cares about money has long been a subject of debate both in Russia and in the West. On government payrolls since his days in the K.G.B., the Soviet intelligence agency, Mr. Putin to many seemed driven more by power and nationalism than by material gain. With access to government perks like palaces, planes and luxury cars, he seemingly has little need for personal wealth.

“If he really does have all that money salted away somewhere, why?” asked Bruce K. Misamore, who was the chief financial officer of Yukos Oil before the Russian government imprisoned its top shareholder, Mikhail B. Khodorkovsky, seized its assets and gave many of them to Mr. Sechin’s Rosneft. “What good does it do him? Is it just ego? Presumably, it’s not to pass it down to heirs. I doubt we’ll see Mr. Putin becoming one of the leading philanthropists in the world.”

And yet, some have drawn attention to what appear to be expensive watches on his wrist and the construction of a seaside palace that the Kremlin denied was being built for Mr. Putin. Some argue that Mr. Putin may want money, or the appearance of it, because it is the measure of stature and power in a society whose transition to capitalism has produced instant billionaires out of the wreckage of Communism.

“I came to the conclusion after time that some of these reports may be seeded by people around Putin himself,” said Fiona Hill, who was the chief Russia expert at the National Intelligence Council and last year co-wrote a book about Mr. Putin. “Russians have to have the biggest and the best. It’s part of the mystique, part of the image.”