Brazil's largest party is abandoning President Dilma Rousseff's government in a decision that diminishes the possibility that she will survive mounting pressure in Congress for her impeachment.

The Brazilian Democratic Movement Party known as the PMDB said on Tuesday that its members are leaving Rousseff's governing coalition. The decision was reported by state news agency Agencia Brasil.

The leader of the Democratic Movement party is Brazil's vice president Michel Temer.

He has vowed to help Rousseff keep her job despite plunging in her popularity amid Brazil's worst recession in decades and a string of corruption scandals.

Temer would assume the presidency if Rousseff is impeached for breaking fiscal laws.