A Supreme Court judge in Brazil has ordered the lower house of congress to create a commission to analyse whether impeachment proceedings against Vice-President Michel Temer should go ahead.
Judge Marco Aurelio Mello overruled a decision by the speaker of the lower house who had rejected the request.
President Dilma Rousseff also faces impeachment proceedings.
It raises the possibility that both the president and the vice-president could be ousted from office.
Tuesday's ruling can be appealed against and overturned by a majority vote by the full Supreme Court.
The request to start impeachment proceedings against Mr Temer was filed back in December by lawyer Mariel Marley Marra.
Mr Marra, who said he was acting as a private citizen, demanded that Mr Temer be impeached over allegations that he manipulated government accounts to hide a growing deficit.
The speaker of the lower house of Congress, Eduardo Cunha, rejected the request saying it lacked merit.
However, Mr Cunha accepted a request to start impeachment proceedings against President Rousseff over similar allegations.
This, Judge Mello ruled on Tuesday, was incorrect. He said that since Mr Cunha had decided to start impeachment proceedings against Ms Rousseff he should have done the same with Mr Temer.
Mr Cunha and Mr Temer are both in the Brazilian Democratic Movement Party (PMDB), which until recently was in an uneasy coalition with President Rousseff's Workers' Party.
The PMDB left the coalition last week and has been highly critical of Ms Rouseff.
Under Brazil's constitution, Mr Temer would become interim president if Ms Rousseff were to be impeached.
Mr Cunha, who would be next in line to succeed Ms Rousseff if both she and Mr Temer were to be impeached, is also facing legal problems of his own.
He has been accused of money-laundering in connection with corruption at the state-run Petrobras oil company.
The fourth in line, Senate leader Renan Calheiros, is also under investigation in connection with the Petrobras corruption scandal.
All four deny any wrongdoing.
Rocky road ahead
Ms Rousseff's impeachment process is currently at the committee stage.
Sixty-five members of the lower house of Congress are debating the merits of the allegations against her.
The committee is expected to vote this month on whether it recommends impeachment hearings to proceed.
When the issue is passed on to the full chamber, her impeachment could still be blocked if one third of the delegates vote against it.
If, however, it is approved by two-thirds of the delegates, the president would be suspended for six months while the matter is passed on to the Senate.