A local research organization has written King Norodom Sihamoni warning him that monks and politics don't mix.
The Cambodian National Research Organization said allowing monks to vote would encourage laymen to choose their temples along party lines, countering the spirit of Buddhism.
If monks have the right to vote, they have the right to hold office, said Heang Rithy, head of the research organization, which cold lead to the politicization of the faith.
"In general, monks cannot participate in the elections," he said. "If you allow monks to vote, that means you allow them to run for office as well. This is against the principles of Buddhism. This amounts to making fun of the religion."
Kuol Panha, executive director of the independent Committee for Free and Fair Elections, disagrees. Monks do have the right to vote but they don't have the legal right to run for office, he said.
"Monks can elect political candidates whom they think will serve Buddhism, but they themselves can't run for office," he said.
Opposition leader Sam Rainsy said monks are capable of objective voting, but they should not participate in political campaigns.
"I personally think that monks have rights like everyone else, to exercise their rights at the polling stations," he said.
Monks have been voting since 1993, and no law forbids it, said Cheam Yeap, a lawmaker for the ruling Cambodian People's Party.
"Monks should be considered as independent voters," Cheam Yeap said. "They can vote. It would be against the Cambodian constitution if you forbid monks from voting."
The constitution allows all men and women of legal age to vote.