Pakistan’s parliament will meet on Friday to consider a no-confidence motion against Prime Minister Imran Khan, according to the lower house speaker’s office, in what appears to be his toughest test since taking office in 2018.

An alliance of opposition parties filed the motion against Khan earlier this month, claiming that he had lost his parliamentary majority due to more than a dozen defections from his party, raising the prospect of political turmoil in the nuclear-armed South Asian country.

The speaker of the lower house of parliament is required by the constitution to convene the session within 14 days of receiving the motion, which would fall on Monday.

But a statement from the speaker’s office said the date was pushed back several days because of a conference of Islamic countries in Islamabad scheduled for March 23.

The opposition accuses Khan of mismanaging the economy and foreign policy. He denies this. No Pakistani prime minister has ever completed his full term in office.

The loss of dissident lawmakers has left Khan about a dozen seats less than the minimum – 172 – needed for a majority. The joint opposition commands 163 seats in the lower house, but could build a majority if most of the defectors effectively join its ranks via a no-confidence vote.

The opposition and political analysts also say Khan has fallen out with Pakistan’s powerful military, whose support is critical for any party to attain power in the way the former cricket star’s upstart party did four years ago.

Khan and the military deny the accusation.