The assembly includes representatives for Venezuelans from all walks of life — fishermen, farmers, students, oil workers — as well as hundreds of local delegates from every municipality, large and small. Many are neophytes who have never held political office before.

But if there is one thing that seems to unite them, it is a will to stifle political dissent.

“There is no possibility that the opposition will govern this country,” Diosdado Cabello, a former military chief who is one of the group’s most powerful members, said Wednesday night on state television.

Mr. Cabello looked into the camera and then added, “Mark my words — no possibility.”

Many details on how the assembly will function still remain unclear, and by Thursday the government still had not announced the names of many of its members. But experts expected it to be lead by an assembly president, and representatives could be divided into committees to write the Constitution.

At least 20 countries have objected to the assembly, which has the power to dismiss any official deemed disloyal or even disband the opposition-controlled national legislature. A software company that helped set up the vote said that the turnout figures announced by the government had been manipulated and inflated by at least a million votes. And large segments of Venezuela have taken to the streets for months to protest against the government, leading to the deaths of at least 120 people.

But the government is intent on moving ahead with the assembly, with some of its members promising to bring order to the country.