Mr. Ponomarev was also a key founder of something called the Congress of People’s Deputies – a kind of Russian parliament-in-exile composed of opposition leaders and other former Duma members. The 93-member body held its first meeting last November outside Warsaw.

“We’re trying right now, firstly, to establish a formal relationship between the congress and the different parliaments of the world. So we’re talking to members of Congress about this,” Mr. Ponomarev says, though when pressed, he won’t name names.

“It’s moving slowly, but still moving. And also, what we want very much to encourage people in Washington to do is to start a discussion about the postwar future of Europe, Russia, in general, how the war would end,” he says.

Mr. Ponomarev, who says he’s “no novice in this city,” is aware of the deep sensitivities around any discussion in Washington about “regime change” in Russia. People here are “extremely reluctant” to discuss this, he says, describing the Biden administration as “extremely cautious.”

In fact, he adds, “I don’t want any other countries to be involved in the regime change. I want this to be the cause for Russians to do.”

Still, he suggests the United States needs to be a bit less reactive in its approach to the war. The weapons supplies to Ukraine are “fantastic,” he says, expressing deep gratitude. “But at the same time, what’s the endgame? This is something that we want to encourage people to think about.”