Washington — It was the eve of Paul Whelan’s fifth Christmas behind bars in Russia when a call came through to a reporter at CBS affiliate WTOP-TV in Washington, D.C., on Sunday.

“I feel alone,” Whelan told the reporter. “I feel that I’ve been left behind.” 

It was a desperate plea from the 53-year-old former Marine detained on espionage charges, and a direct appeal to President Biden following the release of two other Americans — Marine veteran Trevor Reed and WNBA star Brittney Griner — from Russian detainment last year.

Mr. Biden is “the guy that made the decision to leave me behind twice,” Whelan said. “He’s the man that can bring me home.”

Whelan last week also gave a phone interview to the BBC in which he described his situation as “a serious betrayal.”

The native of Novi, Michigan, was first detained by Russian authorities in December 2018 while attending a friend’s wedding. He was convicted in 2020 of espionage and sentenced to 16 years of hard labor.

Both Whelan and the U.S. government have dismissed the charges as “baseless.” The U.S. considers him wrongfully detained.

“Mr. President, you promise to bring me home,” Whelan told WTOP. “I’m still here. There has to be more that you can do to secure my release.”

Whelan remains in a penal colony in the remote Russian province of Mordovia, 350 miles east of Moscow. Last month, he was attacked by a fellow prisoner but not seriously hurt, his brother told CBS News in an email.

Also currently detained in Russia is 32-year-old Evan Gershkovich, an American reporter for the Wall Street Journal held for nearly nine months in pre-trial detention on espionage charges that he, his newspaper and the U.S. government strongly reject.

“All I can say is this: We’re very actively working on it, and we’ll leave no stone unturned to see if we can’t find the right way to get them home and to get them home as soon as possible,” Secretary Blinken told reporters last week.

In a statement provided to CBS News on Monday, Adrienne Watson, a spokesperson for the National Security Council, said that “there is no higher priority for President Biden than bringing home the Americans still wrongfully detained and held hostage abroad, including Paul Whelan.”

In her statement, Watson reiterated what the State Department previously disclosed — that the U.S. has made “significant offers” to Russia for Whelan and Gershkovich, “including one earlier this month” that was rejected by Russia.

“We also continue our conversations with third party countries as we work to find a way to secure their release,” Watson added.