Hasan Jamali, Associated Press
Venezuelan President Nicolas Maduro smiles during a summit of Arab and South American leaders in Riyadh, Saudi Arabia, Tuesday, Nov. 10, 2015. The two-day summit beginning Tuesday aims to improve coordination among political leaders and civil society groups in the two regions, focusing on economics, science and technology, the environment and social and cultural affairs.

WASHINGTON — U.S. senators and leading lawmakers from Latin America are asking Venezuelan President Nicolas Maduro to guarantee free, transparent and democratic parliamentary elections next month.

The 157 legislators from the United States, Brazil, Colombia, Chile, Costa Rica and Peru on Wednesday also asked Maduro to allow election observers from the Organization of American States and the European Union to watch the Dec. 6 vote. They expressed concern that some opposition leaders remain behind bars.

A written copy of the request was delivered to the Venezuelan Embassy in Washington. The mission did not immediately respond to a request for comment.

The legislators' request came one day after OAS Secretary General Luis Almargo declared that Venezuelan authorities were not guaranteeing "a level of transparency and justice" necessary to hold the contest.