Abrego Garcia has drawn national attention after the father of three was shipped out of the country on what federal officials admitted was an "administrative error."
This week, El Salvador President Bukele visited the White House, where he and the Trump administration admitted they have no intention of returning him to the US.
"How can I return him to the United States?" Bukele said sitting next to President Donald Trump in the Oval Office when pressed by reporters about Abrego Garcia's status.
"Am I going to smuggle him into the United States? I'm not going to do it. That question is preposterous. We're not very fond of releasing terrorists."
Van Hollen, who has been steadfast in his determination to bring Abrego Garcia home, booked an early morning flight on April 16 to San Salvador "to let the Trump administration and the government of El Salvador know that we are going to keep fighting to bring (him) home."
"I hope to meet with representatives of the government, and hope to have the chance to see Kilmar and see what his condition is," the senator said from the airport. "We are going to keep fighting because this is a miscarriage of justice.
"The Supreme Court ruled (unanimously) that he was illegally taken out of this country and put in a prison in El Salvador ... This is about due process, and about the rule of law."
Van Hollen previously said that he wanted to meet with Bukele when the president was visiting DC this week.
"I requested to meet with him ... I reached out to the ambassador ... and made it clear I plan to go to El Salvador to discuss the release of this individual who is illegally detained," Van Hollen said.
"A Maryland man who is a father of three is in a notorious prison in El Salvador, and I think the president will recognize why it's important to allow him to return to the United States of America, because it is absolutely unjust and illegal to have this Marylander detained one more day."
Abrego Garcia's wife, Jennifer Vasquez Sura, also issued a plea to the public that was shared by Van Hollen on social media.
"My husband was abducted and disappeared by the Trump Administration ... A court ruled that this, indeed, should have never happened ... They ruled that my life partner Kilmar should have returned home ... but here I am," she said.
"This so-called 'administration error' has destroyed my family's happiness, and my children's innocence.
"Kilmar, if you can hear me, I'm still fighting for you ... Your brother, your mother, our children ... we are still fighting for you and we are not going to give up hope."
Before boarding his flight, Van Hollen had one last word for Trump and his administration.
"This is what bullies do," Van Hollen added. "They begin by picking on the most vulnerable, but if we get rid of the rule of law and due process in the United States, it's a short road from there to tyranny."
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