Powerful MPs in Iran have called for a closed debate on President Mahmoud Ahmadinejad's apparent boycott of his official duties.
The president has not been seen at his office for days, missing two cabinet meetings and cancelling a visit to the holy city of Qom.
Iran's Supreme Leader, Ayatollah Khamenei, recently re-instated a cabinet minister he had pushed out.
Analysts believe an internal power struggle may be under way.
One conservative MP, Gholamreza Mesbahimoghadam, told parliament on Saturday: "Let the Majlis [parliament] do its legal job."
This was a tacit call for Mr Ahmadinejad's impeachment, the BBC's Mohsen Asgari in Tehran says.
Some MPs have accused Mr Ahmadinejad's supporters of putting pressure on ministers to sign a letter backing president against the supreme leader.
Simmering tensions between supporters of the two men came to a head on 17 April, when Intelligence Minister Heidar Moslehi was forced to resign, our correspondent adds.
Mr Moslehi was promptly re-instated by the supreme leader.
Under the constitution, the president is in charge of appointing ministers - who then need to be approved by parliament.
Nearly 300 MPs urged Mr Ahmadinejad, in a letter, to respect Ayatollah Khamenei's decision.
While the president has not been seen at government meetings, Mr Moslehi attended a cabinet meeting last Sunday, the Associated Press news agency reports.
One unnamed reformist politician told the BBC that a "game of chicken" had begun.
"I hope one side yields at the end - otherwise it will move the country toward unprecedented instability that will certainly suck the current Arab uprisings into the country," the politician added.
