It was a weekday morning, two weeks after impeachment proceedings were launched against Brazilian President
Armed with riot gear, the officers lounged on stylish leather furniture, waiting for possible clashes with Rousseff supporters, who were demonstrating outside.
At the other end of the building, indigenous protesters asserting their rights were making their way to the roof.
"We're in a really strange time. On edge. It's a moment in which everyone's mood changes with each new development. No one can calmly get work done," said Congressman Nilson Leitao of the opposition Brazilian Social Democratic Party.
After 20 years of stable government in the fifth most-populous country, Brazil's Congress is now the chaotic center of an unpredictable and explosive political crisis.
Rousseff, 68, a former leftist guerrilla, was elected the country's first female president in 2010 after being handpicked by popular predecessor
But the once-popular president was only narrowly reelected in 2014. Her approval rating began to plunge this year with the country's worst recession in decades, and an inquiry into kickbacks surrounding the Brazilian oil company Petrobras, for which she formerly served as a member of the board of directors.
Pro-impeachment groups organized several large rallies this year, and supporters have sought to answer in kind, despite disillusionment on the left due to austerity and economic hardship. On the same day that Leitao spoke, Fitch Ratings cut the nation's sovereign debt rating to junk status, a major blow to the world's seventh-largest economy.
Politicians and lawyers have been battling over how impeachment will play out, and Rousseff's side won a small victory last week when the Supreme Court invalidated a secret vote on proceedings and gave a bigger role to the Senate, where Rousseff has more supporters.
The chaotic swirl of events was playing out in Congress last week, as legislators checked their phones to monitor the latest plunge in the currency and tens of thousands of supporters marched around the country, including outside the building.
Near the lobby, a Christmas tree in front of the offices of Rousseff's Workers' Party contrasted with a red pamphlet on the wall loudly declaring that the impeachment process represents a coup d'etat and an attack on the constitution.
Legislators were buzzing about the latest report, that Finance Minister Joaquim Levy was leaving the government after disagreements with Rousseff over his austerity policies. (He was quickly replaced with a close ally of the president, Planning Minister Nelson Barbosa.)
The political pandemonium has been reverberating powerfully in Congress.
In recent days, demonstrations over the impeachment initiative have led to physical confrontations and broken voting machines. The home of House speaker Eduardo Cunha, who has led the impeachment effort against Rousseff, was raided this month by police investigating the Petrobras scandal.
"Now, for Brazil to really start over, to have a new start, the best of all would be a new election," said Leitao, the opposition congressman.
Lawmaker Orlando Silva of the Communist Party, a member of Rousseff's coalition, said the crisis is larger than the paralysis in Congress.
"The leaders in Congress don't control their parties. Ministers have little influence … and the criminal investigations that are being carried out by the federal police have discredited the government," he said.
In fact, he said, investigating and punishing corruption should be celebrated.
"Things are changing," Silva said. "That will be understood in the future. But for now it's producing distrust among the population."
Upstairs, in a much more stylish wing of offices, Workers' Party Congressman Paulo Teixeira predicted there will be no solution to the crisis before March.
"The way out of the impeachment is to defeat the impeachment," he said. "In a presidential system, impeachment has to do with a crime committed. And [Rousseff] has committed no crime."
Texeira blamed the crisis on an attempt by the political opposition to seize the power it failed to win through the last presidential election. "The opposition never accepted their defeat," he said. "They've tried everything to stop the government. Impeachment is their last attempt."
Back downstairs, a crowd was milling outside as the sun set. A man in a suit slept on a couch. He and the crowd were ignoring an alarm that had been buzzing from somewhere for almost 45 minutes. It sounded like a fire alarm.