ISLAMABAD (AP) — Pakistani lawmakers were choosing Wednesday new members of the country's Senate, or upper house of parliament — a vote that is seen as a test for Prime Minister Imran Khan's government.

Khan's ruling Pakistan Tehreek-e-Insaf party is seeking to improve its standing in the 104-member Senate, where it lacks majority. Votes are cast by members of the National Assembly, or the lower house of parliament, and four provincial assemblies.

In Pakistan, members of the Senate are elected for six-year terms and as half the senators are due to retire after three years, elections are required to replace 52 Senators who had completed their terms. However, voting on Wednesday was being held only for 37 seats as other candidates had ran unopposed.

Members of the provincial assemblies and the National Assembly are elected in nationwide parliamentary elections, which last time took place in 2018, bringing Khan's party to power.

Both chambers of parliament have legislative powers, and any bill passed by the National Assembly must be approved by the Senate before it becomes a law. In turn, any legislations by the Senate goes to the National Assembly, where Khan has a simple majority.

The most interesting race was the one between the opposition’s joint candidate Yusuf Raza Gilani, a former prime minister, and Hafeez Sheikh, an adviser to Khan on finance. As polling kicked off, Khan showed up in parliament in person on Wednesday to cast his vote for Sheikh.

However, Fawad Chaudhry, minister for science and technology, predicted an easy win for the opposition and Sheikh.