Dissidents in Malaysia’s ruling party clamored for the prime minister to resign Wednesday after opposition leader Anwar Ibrahim returned to Parliament with a sweeping election victory.

Anwar regained his Parliament seat in the north by a landslide in Tuesday’s by-election, delivering a demoralizing defeat for the government. His success came on the heels of big gains made by the opposition in the March general election.

“I am glad to be back after a decade,” said Anwar, who was forced to resign his Parliament seat in 1999 amid a sodomy allegation.