PHNOM PEHN, Cambodia (AP) — Cambodians have begun voting in an election virtually certain to return to office Prime Minister Hun Sen and his ruling Cambodian People's Party.

Although 20 parties are contesting the polls, the only one with the popularity and organization to mount a credible challenge, the Cambodian National Rescue Party, was dissolved last year by the Supreme Court.

Its former leaders have called on supporters to boycott the polls.

Voting ends at 3 p.m. and preliminary results are expected on Sunday night.