ISLAMABAD (AP) — Pakistan's prime minister will seek a vote of confidence from the National Assembly this weekend to prove he still has the support of majority lawmakers in the house, despite the defeat of his ruling party's key candidate in Senate's elections, a Cabinet minister said Thursday.

If Prime Minister Imran Khan fails to win the vote of confidence, Pakistan could face another phase of political turmoil. According to Chaudhry Fawad Hussain, science and technology minister, the vote is due on Saturday. Khan is to address the nation later on Thursday evening.

The development comes a day after the ruling Tehreek-e-Insaf party's candidate Hafeez Sheikh lost a hotly contested election for a seat in the Senate, or upper house of parliament, against former Prime Minister Yusuf Raza Gilani, who won in a 169-164 vote.

Senate elections were seen as a test for Khan, who came to power in the 2018 parliamentary elections. Though Khan improved his standing in the 100-member Senate, Sheikh’s defeat was a setback for his government.

Hussain, the science and technology minister, also said that senators are expected to vote in the coming days on a new chairman of the Senate. The incumbent, Sadiq Sanjrani, is to be the ruling party's candidate again. Gilani is likely to contest the vote for the chairman. He served as prime minister from 2008 to 2012.

Gilani’s success in the Senate indicates that some of the ruling party's lawmakers had rebelled and did not vote for Sheikh. Votes for the Senate are cast by members of the National Assembly, or the lower house of parliament, and four provincial assemblies.