A fifth Venezuelan opposition party has pulled out of Sunday's congressional elections, saying it is concerned the balloting will not be fair.

The New Era party has joined the opposition boycott, just days after the Democratic Action, Project Venezuela, Copei, and Justice First parties announced their withdrawal.

Opposition parties say they are boycotting the vote because the electoral council is biased. They also say the electronic voting machines do not guarantee confidentiality.

The government said Friday the vote will go forward on Sunday as planned with the Organization of American States and the European Union observing the electoral process. The government statement also said the National Electoral Council has agreed to a set of 11 changes in response to opposition concerns.

Meanwhile, U.S. State Department spokesman Sean McCormack has again denied any U.S. involvement in the withdrawals.