Phnom Penh, Cambodia (CNN) -- Cambodians went to the polls Sunday for an election whose outcome is all but certain: five more years in power for long-serving Prime Minister Hun Sen.
Hun Sen has been in office for 28 years. And so confident was he of victory, he didn't bother campaigning ahead of the elections.
Still, opposition groups were energized.
The three main parties teamed up, and hoped for strength in numbers: Enough votes to take over control from the ruling party.
More than 9 million people were eligible to vote.
The excitement bubbled over Friday when opposition leader Sam Rainsy returned home from exile in France.
He left in 2009 to avoid prison on charges of spreading disinformation -- charges many considered politically motivated. International pressure led to him receiving a royal pardon last week. But he arrived too late to run for office.
On election day, opposition parties alleged that widespread irregularities had marred the balloting.
At a local high school in Phnom Penh, the names of voters registered with the opposition parties were either missing or misspelled -- meaning they couldn't vote.
The national election committee said it worked hard to ensure the election was far.
"In preparing for the election this year, we started in the middle of 2012," said Tep Nytha, the secretary general of the committee, ahead of the balloting.
Opposition supporters told CNN that if they end up losing the election due to voter fraud, they will appeal the results -- but do so in a peaceful way.
They will take their grievance to the United Nations, they said, rather than to the streets.
Final results are expected to be announced later Sunday.