Demonstrators take part in a protest against Brazil's President Jair Bolsonaro in Sao Paulo, Brazil, on Tuesday. Photo: VCG

Supporters of Brazilian President Jair Bolsonaro tore down a police blockade Monday night in downtown Brasilia, police said, on the eve of massive demonstrations that have the country on edge.

Fighting record-low poll numbers, Bolsonaro is seeking to mobilize his base, particularly at the protests in Brasilia and Sao Paulo. The far-right leader plans to attend both rallies on Tuesday, Brazil's Independence Day, as he tries to build pressure on the supreme court over investigations into him and his inner circle. 

Hundreds of people arriving to participate in Tuesday's protests "broke through containment barriers" and entered the avenue leading to the National Congress and Supreme Court (STF) buildings, according to the federal district police.

The avenue had been closed to traffic as a security measure.

In videos posted on social media and shared by local news outlets, a small caravan of cars and trucks was seen entering the Ministries Esplanade, cheered on by protesters walking and waving Brazilian flags.

"We just invaded! The police could not contain the people! And tomorrow we are going to invade the STF," one walking protester shouted.

The marches have monopolized public debate in Brazil, including warnings to avoid something similar to the January 6 attack on the US Capitol by supporters of former president Donald Trump.

Bolsonaro has often drawn comparisons to Trump.

Police reported they were still at the scene. In images shown by CNN Brazil, the situation appeared to be under control. The federal district government has organized an operation with 5,000 police officers to protect public buildings and help avoid riots.