Brazilian President Jair Bolsonaro called huge rallies for the country's independence day, seeking to fire up his far-right base.

Supporters of Brazilian President Jair Bolsonaro pushed through police barriers to advance towards Congress in Brasilia on Monday night, the eve of a day of planned demonstrations to back the far-right leader in his dispute with the judiciary.

Trucks honked their horns as hundreds of Bolsonaro supporters dressed in the green-and-yellow national colors cheered them through, videos posted on social media showed.

But they failed however to reach their target of surrounding the Supreme Court, which some demonstrators have planned to occupy in a protest modeled on the Jan. 6 assault on the U.S. Capitol by supporters of then-President Donald Trump.

The square of the Supreme Court building remains closed off by barriers and a line of police, the city’s security department said.

Thousands of demonstrators are expected to march in the capital on Tuesday - Brazil’s independence day - and in the financial center Sao Paulo to support Bolsonaro in his clash with the judiciary over changes to the voting system.

Critics fear the president is encouraging supporters to the point that they might try to invade the court.

More than 150 left-leaning former presidents and party leaders from across the globe signed an open letter criticizing Bolsonaro for encouraging what they called an imitation of the Jan. 6 storming of the U.S. Capitol, staged by Trump supporters after he gave a speech falsely claiming his election defeat was the result of fraud.

The demonstrations are “stoking fears of a coup d’état in the world’s third-largest democracy,” the letter said.

Bolsonaro said on Friday the demonstrations will be an ultimatum to the Supreme Court justices who had taken what he called “unconstitutional” decisions against his government.

The court has authorized investigations of Bolsonaro allies for allegedly attacking Brazil’s democratic institutions with misinformation online. He has called the court-ordered probes a violation of free speech rights.

Congress and the courts also resisted Bolsonaro’s attempt to introduce paper voting receipts as a backup to an electronic voting system which he says is vulnerable to fraud. The electoral court maintains the system is transparent and safe.

Bolsonaro’s critics say he is sowing doubts so he can challenge the results of next year’s election, which opinion polls now show him losing to former President Luiz Inacio Lula da Silva. Neither has confirmed his candidacy.

In a speech on social media on Monday, the leftist Lula said the president on Independence Day should offer hope of economic recovery and solidarity with the victims of COVID-19.

“Instead of announcing solutions, he is calling people to confrontation…in acts against democracy,” Lula said, accusing Bolsonaro of sowing “division, hatred and violence.”

Brasilia will have 5,000 police and military personnel on hand to maintain order at the rally outside Congress, where Bolsonaro is scheduled to appear on Tuesday morning.

In the afternoon, Bolsonaro will join supporters on a major avenue in Sao Paulo at a gathering that he has billed as the biggest political rally in Brazilian history.

Many leftist leaders have urged their followers to avoid clashes by skipping counter-demonstrations on Tuesday in favor of larger anti-Bolsonaro protests on Sept. 12.

Financial, industrial and agribusiness leaders have also distanced themselves from Bolsonaro’s attacks on the Supreme Court and called for dialog between the executive and judiciary.