Pakistanis have labeled it a “selection” — not an election. Human rights monitors have condemned it as neither free nor fair.

As voters headed to the polls on Thursday, the influence of Pakistan’s powerful military and the turbulent state of its politics were on full display. Few doubted which party would come out on top, a reflection of the generals’ ultimate hold on Pakistan’s troubled democracy.

But the military is facing new challenges to its authority from a discontented public, making this an especially fraught moment in the nation’s history.

The tension was underlined on Thursday as Pakistan’s Interior Ministry announced that it was suspending mobile phone service across the country because of the security situation. Some analysts in Pakistan cast it as an effort to keep opposition voters from getting information or coordinating activities.

The election was taking place in the shadow of a monthslong military campaign to gut the party of former Prime Minister Imran Khan, a former international cricket star and populist leader who was ousted by Parliament in 2022 after falling out with the generals.

The crackdown is the latest dizzying swerve in the country’s roller-coaster politics.

The Pakistan Muslim League-Nawaz, or P.M.L.N., the party of the three-time former prime minister Nawaz Sharif, is expected to claim victory in Thursday’s vote. Mr. Sharif himself was ousted when he fell out of favor with the military in 2017, and Mr. Khan, with the military’s support, became prime minister a year later.