A key figure in Portugal's centre-right coalition, Foreign Minister Paulo Portas, has quit government just a day after the finance minister.
Mr Portas, head of the coalition's junior party, had been given the task of overseeing cuts after Finance Minister Vitor Gaspar quit on Monday.
In his resignation letter, Mr Portas said he disagreed with Prime Minister Pedro Passos Coelho's austerity path.
Portugal is struggling to meet the terms of its 78bn euro bailout in 2011.
The country has been in recession for two years and the economy is expected to contract by 2.3% this year.
Last week a general strike brought public transport to a halt.
The prime minister's choice of Treasury Secretary Maria Luis Albuquerque to replace Mr Gaspar was interpreted by many as meaning he intended to press ahead with cuts.
"The prime minister has chosen to maintain its path at the finance ministry," Mr Portas said in his letter.
"I respect this choice but I disagree. I expressed this view to the prime minister who nevertheless confirmed his choice."
To remain in the government would be an "act of simulation... neither politically viable nor desirable", he added.
Mr Portas has in the past objected to plans to raise taxes on pensioners.
It was not immediately clear what effect the resignation would have on relations between Mr Portas's party, the CDS-PP, and the prime minister's Social Democrats.
The coalition has been in power for two years.
Mr Gaspar, the man seen as the architect of austerity in Portugal, said in his own resignation letter that he was leaving because of the growing erosion of public support for austerity measures.