Romanians are voting Sunday in a referendum to decide whether to impeach their president in a bitter feud between center-right President Traian Basescu and his rival, center-left Prime Minister Victor Ponta.

The president's opponents have accused him of overstepping his powers and violating the country's constitution. After Romania's parliament suspended Mr. Basescu earlier this month, Mr. Ponta's Social-Liberal Union took power and immediately moved to remove the president.

Mr. Basescu says the impeachment process is a political vendetta.

The United States has led Western concern that Mr. Ponta's coalition government has been eroding Romania's freedoms.

If voter turnout is lower than 50 percent, the referendum will be declared invalid and Mr. Basescu will be reinstated and continue his term, which ends in 2014.