US senator Bernie Sanders on Thursday urged Brazilians of all stripes to respect the outcome of presidential elections and reject political violence, in a message tweeted by fellow leftist Luiz Inacio Lula da Silva.

Leading in the opinion polls, ex-president Lula will be facing incumbent Jair Bolsonaro in a first round of elections on Sunday.

“As the largest democracy in Latin America, your nation stands as an important example to the world of a stable and fair electoral system,” Sanders said in a recorded message.

“It is one where both the winners and the losers of elections must respect the results and where political violence or the threat of political violence is always unacceptable.”

Sanders sought to impart on Brazilians the importance of voting “at a time that democracies all over the world are under attack and we are seeing nations move towards authoritarianism.”

On Wednesday, the US Senate passed a Sanders-backed resolution stressing Washington would not support “any government that comes to power through undemocratic means” amid fears Bolsonaro would not accept a loss and could foment violence.

The far-right president has said “only God” can unseat him, and that his reelection bid can have one of only three outcomes: “prison, death or victory.”