UNITED NATIONS — In a setback for its increasingly popular president, Venezuela was unable to marshal enough support yesterday to win a seat on the U.N. Security Council.

A routine U.N. General Assembly vote on the five of the 10 elected seats on the Security Council turned dramatic as neither Venezuela nor its rival for the Latin American council seat, Guatemala, won the necessary support of two-thirds of the 192 assembly members.

Yesterday’s secret General Assembly process resembled a day at the races, with one-minute rounds of voting. Separating them were 20-minute intervals, as paper ballots were counted and delegates exchanged opinions, sipped espresso in the nearby lounge, and lobbied each other.

During the early morning rounds, Venezuelans handed out small packets of Venezuelan-made chocolate while Guatemalans gave away colorful wristbands made of beads. Some Muslim delegates said they put off eating the chocolate until sundown as part of the daily Ramadan fast.

Behind the scenes, however, was intense lobbying, with Venezuela promising oil deals, America — which supported Guatemala’s candidacy — pledging political incentives, and both sides threatening retaliation for those who voted against them. The result was, in the words of one Venezuelan diplomat, a “roller-coaster ride.”

The race was closely watched in Caracas, where a national presidential election is scheduled for early next year. President Chavez has invested his prestige and petrodollars in the Security Council race, and some of his fiercest anti-American rhetoric has been reserved for it.

Yet Mr. Chavez’s famous September speech at the U.N. General Assembly, in which he called President Bush “el Diablo,” could have hurt his country’s candidacy.

“You have to work within certain parameters,” the Panamanian ambassador to the United Nations, Ricardo Arias, said.The speech led many diplomats to believe that if Venezuela gained a Security Council seat, Mr. Chavez would go too far to split the council and render it ineffective, Mr. Arias added.

“We are fighting against the biggest power on the planet,” the Venezuelan ambassador to the United Nations, Francisco Javier Arias Cardenas, said. “The U.S. is fighting us as if we were holding a nuclear bomb to destroy it.”

Guatemala began the day with 109 supporters, 15 votes shy of the twothirds majority needed to win the seat. Venezuela, which until yesterday was acting as if its election were assured, received only 76 votes in the first round.

In later rounds, the rivals moved to a 93–93 tie. After 10 rounds, however, Guatemala was back in the lead, with 110 supporters to Venezuela’s 77.

Mr. Cardenas vowed to preserve his country’s “dignity” and said Venezuela would hang onto its core group of supporters “until the last moment.” But the Guatemalan foreign minister, Gert Rosenthal, said,”If this goes on for days and neither party gets the two-thirds, both should withdraw for a third candidate.”

In October 1979, the General Assembly went through a record 154 rounds of voting as Cuba and Colombia vied for a council seat. Both finally withdrew in January 1980 after Mexico stepped in as a compromise candidate.

At one point yesterday, as the assembly seemed deadlocked, one country voted Mexico in, only to be countered in the next round by a vote for Cuba. Most diplomats said publicly that for now, the contest is between Venezuela and Guatemala, but that at least three countries — Costa Rica, the Dominican Republic, and Uruguay — could enter the race.

Earlier yesterday, South Africa, Italy, Belgium, and Indonesia easily won enough votes for council seats. But after 10 rounds of voting for the Latin American seat, the president of the General Assembly, Sheikha Haya Rashed Al Khalifa, called a halt to the voting until today.

“In the year 2000, I spent 31 days in Florida. This has just begun,” the American ambassador to the United Nations, John Bolton, said.