The attack on Brazil’s seat of government resembles the storming of the U.S. Capitol on Jan. 6, 2021.

A defeated president claims, falsely, that an election was rigged. After months of baseless claims of fraud, an angry mob of his supporters storms Congress. They overwhelm police and vandalize the seat of national government, threatening the country’s democratic institutions.

Similarities between Sunday’s mob violence in Brazil and the attack on the U.S. Capitol on Jan. 6, 2021, are self-evident: Jair Bolsonaro, the right-wing former president of Brazil, had for months sought to undermine the results of an election that he lost, in much the same manner that Donald J. Trump did after his defeat in the 2020 presidential election. Trump allies who had helped spread falsehoods about the 2020 election have turned to sowing doubt in the results of Brazil’s presidential election in October.

Those efforts by Mr. Bolsonaro and his allies have now culminated in an attempt — however implausible — to overturn the results of Brazil’s election and restore the former president to power. In much the same manner as Jan. 6, the mob that descended on the Brazilian capital overpowered police at the perimeter of the building that houses Congress and swept into the halls of power — breaking windows, taking valuable items and posing for photos in abandoned legislative chambers.

The two attacks do not align completely. The Jan. 6 mob was trying to stop the official certification of the results of the 2020 election, a final, ceremonial step taken before the new president, Joseph R. Biden Jr., was inaugurated on Jan. 20.

But Luiz Inácio Lula da Silva, the new president of Brazil, was sworn into office more than a week ago. The results of the presidential election have been certified by the country’s electoral court, not its legislature. There was no official proceeding to disrupt on Sunday, and the Brazilian Congress was not in session.

The mob violence on Jan. 6, 2021, “went right to the heart of the changing government,” and the attack in Brazil is not “as heavily weighted with that kind of symbolism,” said Carl Tobias, a professor of constitutional law at the University of Richmond.

And Mr. Bolsonaro, who has had strong ties with Mr. Trump throughout their years in office, was nowhere near the capital, having taken up residence in Orlando, Fla., about 150 miles from Mr. Trump’s estate at Mar-a-Lago in Palm Beach.

Nevertheless, the riot in Brasília drew widespread condemnation, including from U.S. lawmakers, with many Democrats drawing comparisons between it and the storming of the U.S. Capitol.

“Democracies of the world must act fast to make clear there will be no support for right-wing insurrectionists storming the Brazilian Congress,” Representative Jamie Raskin wrote on Twitter. “These fascists modeling themselves after Trump’s Jan. 6 rioters must end up in the same place: prison.”

Representative George Santos, a Republican from New York under criminal investigation by Brazilian authorities, appeared to be one of the first elected officials from his party to condemn the mob violence in a post on Twitter on Sunday, but he did not draw a connection to Jan. 6.

Many of the lawmakers who condemned the violence had lived through the attack on the Capitol that occurred just over two years ago. Mr. Raskin was the lead impeachment manager in Mr. Trump’s second impeachment trial over his role in inciting the mob.

In a final echo of the Jan. 6 attack on Sunday, hours after the riot in Brazil began, Mr. Bolsonaro posted a message on social media calling for peace, much the way Mr. Trump did. Authorities had already announced they had the situation under control.