Brazilian President Dilma Rousseff

The lower house of Brazil’s Congress voted on Tuesday to appoint a committee stacked with opponents of President Dilma Rousseff to report on whether to impeach her, a setback for the leftist leader who is battling for political survival.

In a secret ballot, lawmakers voted 272-199 for a list of committee members drawn up by the opposition and pro-impeachment members of the centrist Brazilian Democratic Movement Party (PMDB), Rousseff’s main ally in her governing coalition.

While the result was a hard blow for Rousseff, the fact that 199 lawmakers voted for the pro-government list was an indication that she may still have the more than one-third of support needed to block an eventual impeachment vote before the full house.

Her supporters in Congress plan to appeal to the Supreme Court against the secret voting procedure adopted by Speaker Eduardo Cunha, who allowed the alternative list to be presented.

Controversy over the vote descended into chaos on the floor of the house, as some lawmakers outraged by the secret vote smashed an electronic voting urn and unplugged others, while pro-impeachment parties waved a flag in celebration of the win.

The committee will have the task of reporting on whether Rousseff committed an impeachable offence. Opponents who filed the impeachment motion that set the process in train accuse her of breaking budget rules to boost spending during her re-election campaign last year. Rousseff has denied any wrong-doing.

If the committee finds an offence was committed, the process will go to a full vote on the house floor, at which the opposition needs two thirds of the votes to begin a 180-day impeachment trial in the Senate. During that trial the president would be suspended and replaced by her vice president, Michel Temer.