Vice President Mike Pence is shown in a camera phone as he walks along the rope line to talk to people attending his speech on the crisis in Venezuela at Rice University's Baker Institute for Public Policy on Friday, April 5, 2019, in Houston. (Brett Coomer/Houston Chronicle via AP)

HOUSTON - Vice-President Mike Pence said Friday during a visit to Texas that Venezuelan President Nicolas Maduro "must go" because of the "suffering he has brought" to the people of that country.

"The struggle in Venezuela is between dictatorship and democracy, but freedom has the momentum. Nicolas Maduro is a dictator with no legitimate claim to power, and Nicolas Maduro must go," Pence said at the Baker Institute at Rice University in Houston, named for former Secretary of State James Baker.

Houston is home to a large Venezuelan immigrant community, as well as the corporate headquarters of CITGO, a subsidiary of Venezuela's state-run oil giant PDVSA. Pence earlier this week called for the release of six CITGO executives who've been jailed in Venezuela for more than a year without trial. Pence has said the five American citizens and one legal permanent U.S. resident , all with roots in Texas and Louisiana, are being "illegally detained." Pence said some of their relatives were at his speech Friday in Houston.

The U.S. and about 50 other countries contend Maduro's election last year was illegitimate and that support opposition leader Juan Guaido's claim to the presidency.

Pence Friday said that "for far too long the people of Venezuela have suffered under the heavy hand of oppression." He noted there's been a mass exodus from the country, with more than 3 million abandoning it so far. He said that "for those who stay behind, it is a society of lawlessness, corruption, crime and violence."

The U.S. on Friday added two oil-sector companies and 34 vessels to a sanctions list aimed at forcing Maduro to step down. A Treasury Department announcement said the companies and vessels are being used to ship fuel to Cuba or in other aspects of the oil industry and help support the Maduro government.

Pence said the only way Maduro "clings to power" is with the help of Cuba.

"All options are on the table," Pence said. "We will not stand idly by while the Venezuelan people suffer under dictatorship and oppression. And Nicolas Maduro would do well not to test the resolve of the United States of America."

Earlier Pence made a stop in Houston to thank U.S. Immigration and Customs Enforcement agents for their service. He's set later Friday to head to the George H.W. Bush Presidential Center in College Station where he'll participate in a discussion on the American vice presidency with former vice-presidents Dick Cheney and Dan Quayle.

News from © The Associated Press, 2019