Sen. Marco Rubio (R., Fla.) warned U.S. lawmakers and other officials against trying to open a backchannel with Venezuelan President Maduro as the Trump administration and regional allies work to ratchet up sanctions and form a united front against his regime.

Sen. Dick Durbin (D., Ill.) and Rep. Pete Sessions (R., Texas) quietly traveled to Venezuela last week on separate trips.

The lawmakers met with Maduro and other high-level officials in Caracas in an attempt to win the release of at least one hostage, Josh Holton, a Utah man imprisoned in Venezuela for nearly two years on what the U.S. government has deemed false weapons charges.

Maduro's government also detained several Venezuelan-Americans with dual citizenship shortly before Thanksgiving last year. Those individuals, all former Citgo executives, were imprisoned while attending a Citgo meeting in Caracas and charged with treason.

Rubio, who chairs the Senate Foreign Relations Western Hemisphere subcommittee, for weeks has been trying to convince his congressional colleagues not to engage directly with the Maduro regime.

The Florida Republican says he is sympathetic to the plight of Holt and other U.S. citizens, but said the regime is using the hostages as pawns because it is growing more desperate and losing power as the humanitarian crisis in the country worsens.

Rubio argued that the Maduro regime is only trying to meet with U.S. officials to legitimize his power to his countrymen and also to try to extract concessions from the United States and stave off additional sanctions to its oil sector.

Only the Trump administration, which has slapped several layers of sanctions on the Maduro regime over the last year, has the power to make deals with the Venezuelan government, and it will not engage in these types of negotiations, Rubio said in a statement to the Washington Free Beacon.

"There is no Maduro backchannel with anyone in the U.S. government with the power or the authority to make any deal or offer any concessions," Rubio said. "President Trump is not going to be tricked into making some ridiculous concessions."

"I too want Joshua Holt released and returned home immediately," he said. "But I have zero doubt that as long as Trump is president, the only way sanctions are lifted is if Maduro leaves power, the National Assembly is restored, and free and fair elections for a new president are scheduled."

Spokespersons for Durbin and Sessions did not respond to a Free Beacon request for comment.

Durbin's office on Saturday told the Chicago Sun Times that he traveled to Venezuela to better understand the humanitarian crisis taking place there and to urge Maduro to implement democratic reforms ahead of a "snap election" the president scheduled for May.

The oil-rich South American country was previously affluent but in recent years economic mismanagement by Maduro's socialist government has created a depression, massive debt, skyrocketing inflation, and a severe drop in oil prices. Even though food and medicine are scarce, the Maduro government has rejected U.S. offers to provide these resources.

A Durbin spokesperson confirmed that the senator met with Maduro, as well as members of the opposition, the president of the National Assembly, the ministers of Health and Nutrition, business leaders, civil society groups, doctors, and humanitarian organizations.

"The Venezuelan and American people share a long and deep friendship. I traveled to Caracas to better understand the conditions faced by Venezuelans and to urge President Maduro to adhere to basic democratic norms, particularly regarding the dubious snap election now scheduled for May," Durbin said in a statement.

Durbin said he pointed out that there is "bipartisan agreement" in Washington on the economic, political, and humanitarian problems in Venezuela.

"I was heartbroken by what I saw and heard, particularly regarding the collapse of the country's ability to feed and medically care for its people and children," Durbin said. "Unfortunately, failure to address these issues, hold a credible election, and free Venezuelan political prisoners and Josh Holt will only further isolate Venezuela internationally and strain relations with the United States."

Durbin and other U.S. lawmakers from both sides of the aisle have decried Maduro's abrupt decision to hold elections in May, which were originally scheduled for 2020.

The visits from the U.S. lawmakers and Rubio's warning comes ahead of this week's Summit of the Americas, which will take place in Peru on Thursday and Friday. The trip will serve as President Trump's first to South America.

The Peruvian government has taken the unprecedented step of excluding the Mauro regime from the summit, citing regional leaders concerns about his government’s departure from constitutional democracy.

Maduro last year moved to consolidate power by engineering the creation of a new lawmaking body comprised solely of his supporters. Opponents denounced the move as undemocratic and in violation of the country's constitution.

The United States and its regional allies have been using the run-up to the Summit of the Americans, a meeting of top heads of state from the Western hemisphere, to ratchet up the pressure against Maduro.

Panama recently took steps to punish Maduro and his cohorts, placing Maduro and other top officials and Venezuelan companies on a watch list for money laundering. Panama pulled its ambassador from Venezuela on Friday in retaliation for the Maduro government banning key Panamanian business from operating within its borders.

State Department spokeswoman Heather Nauert applauded the move, congratulating Panama for its vigorous defense of democracy and human rights and for "promoting stability in the hemisphere."

"The United States urges others in the hemisphere to stand with Panama and to take action in support of the Venezuelan people and their right to have their voices heard in free, fair and transparent elections," she said in a statement.

Developing a unified, regional approach to sanctions against Caracas is a top agenda item for the Summit.

The European Union and Canada also have imposed sanctions against Venezuela in recent months, and a dozen Latin American countries led by Peru known as the Lima Group have signaled they will follow suit if Maduro does not agree to their demands to guarantee free and fair elections.

Ahead of President Trump's attendance at the summit, his first visit to the region as president, a senior administration official this week said the forum will "provide space for our leaders to address the most pressing issues of the hemisphere, and we believe the humanitarian crisis in Venezuela is the most pressing issue at this time."

"We hope that the region will continue to take action to get Venezuela on the path to democracy, security, and prosperity," the official added.