The brother of U.S. national Paul Whelan, who has been imprisoned in a Russian labor camp since his 2018, said his family has a renewed sense of hope after U.S. Secretary of State Antony Blinken revealed that he has offered a "substantial proposal" for the return of Whelan and fellow American WNBA star Brittney Griner.

Blinken announced this week that the Biden administration made the proposal weeks ago and is hoping to speak to Russian Foreign Minister Sergey Lavrov for the first time since Feb. 15. Blinken did not offer details on the nature of the proposal, but the possibility of a prisoner swap has been rumored.

Whelan's twin brother – who has spoken out against the State Department for dragging its feet on Paul's release – welcomed the news on Thursday in an interview with "America Reports."

US OFFERS ‘SUBSTANTIAL PROPOSAL’ TO BRING BRITTNEY GRINER, PAUL WHELAN HOME FROM RUSSIA

Paul Whelan Russia

Paul Whelan, a former US marine accused of espionage and arrested in Russia in December 2018, stands inside a defendants' cage as he waits to hear his verdict in Moscow on June 15, 2020.  (Photo by KIRILL KUDRYAVTSEV/AFP via Getty Images)

"We don't always get an insight into what the U.S. government, the State Department, the National Security Council is doing on Paul's case," David Whelan said. "And I think for a lot of families it can mean when you don't hear anything that you're not confident that something is happening."

One name mentioned as a possible candidate for a prisoner swap is Viktor Bout, a Russian arms dealer known as the "Merchant of Death," who is serving a 25-year sentence after being convicted of conspiracy to kill U.S. citizens and providing aid to a terrorist organization. Experts have warned about a deal including Bout over the consequences it may have on American travelers.

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Whelan acknowledged that his brother's release could come at a cost.

"It's a hard call. Fortunately, I'm not the president of the United States," he said. "But if the president makes that difficult decision, I would absolutely support Paul's release, if that's what was the outcome of it. I don't really know what the State Department has offered or the U.S. government has offered. They talk about a substantial offer, and it may be that person, it may be other people. The Russians have been very clear about what they want, but there are a number of other items and so it'll be interesting to see what it actually is."

Brittney Griner testifies on her behalf

American basketball star Brittney Griner returned Wednesday to a Russian courtroom for her drawn-out trial on drug charges that could bring her 10 years in prison of convicted. (AP Photo/Alexander Zemlianichenko, Pool)

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Whelan said his family is hopeful that the Russians are receptive of Biden's offer so they can bring his brother home and get him the medical care he needs.

"He's lost weight. They've cut back food rations at the prison, so they're not eating as well, although it was never very nutritious," he said. "It's a pretty hard life. And I don't think it will be getting any easier so long as Russia is continuing to attack Ukraine."

Paul Whelan, a corporate executive from Michigan and former U.S. Marine, was arrested in 2018 on charges of espionage. He was sentenced to 16 years of hard labor in 2020. He and his family have vigorously asserted his innocence. The U.S. government has denounced the charges in Russia as false.