Key ally of Brazil's president divided over her impeachment

Rousseff also said she had no reason to distrust Vice President Michel Temer of the PMDB party, who has not publicly taken a position on her impeachment.

If two-thirds of house members vote for impeachment, the president would be suspended pending a 180-day trial in the Senate, while the vice president runs the country.

Temer's public silence and the resignation of Civil Aviation Minister Eliseu Padilha, a senior PMDB member, from Rousseff'scabinet on Friday led to speculation that Temer is positioning himself to become president if she is impeached.

"We have to see what the majority of the party thinks. At the moment, (Temer) is beginning that assessment," Padilha told journalists on Monday.

Temer wrote a personal letter to the president regarding the government's distrust of him and the PMDB, according to a statement from his office late on Monday. The vice president called for national unity and did not propose a break between parties or the government, his office said in the statement.

The president's office confirmed Padilha's resignation and said the civil aviation ministry's executive secretary,Guilherme Walter Ramalho, would take over as interim minister.