President Biden meets with Griner, Whelan families

President Joe Biden met Friday at the White House with the families of Brittney Griner and Paul Whelan, two American citizens who remain detained in Russia.

White House Press Secretary Karine Jean-Pierre offered a readout of President Biden's meeting with Cherelle Griner and Elizabeth Whelan, saying Biden "appreciated the opportunity to learn more about Brittney and Paul from those who love them most, and acknowledged that every minute they are being held is a minute too long."

"The President held the meetings to reiterate his continued commitment to working through all available avenues to bring Brittney and Paul home safely. He asked after the wellbeing of Elizabeth and Cherelle and their respective families during this painful time," Jean-Pierre said in the statement.

"We all admire the courage of the Whelan and Griner families in the face of these unimaginable circumstances, and we remain committed to reuniting them with their loved ones," she added.

The Biden administration said in July that it had made a "substantial proposal" to Russia to have Griner and Whelan returned to the U.S. but Jean-Pierre said no breakthroughs were expected at Biden's meeting.

"So, while I would love to say that the purpose of this meeting is to inform the families that the Russians have accepted our offer, and we are bringing their loved ones home, that is not what we're seeing in these negotiations at this time," Jean-Pierre said.

"Look, as we have said, the Russians should accept our offer. They should accept our offer today. We will keep working diligently until the day we get to share that good news," she added.

Still Jean-Pierre said Biden wanted to let the families know they remain "front of mind" for the administration.

"So one of the things that the president wanted to -- to make clear is and one of the reasons he's -- he is meeting with families is that he wanted to let them know that they remain front of mind and that his team is working on this every day on making sure that Brittney and Paul return home safely. One family member was already scheduled to be in town and the president wanted to meet with both of the families on the same day," Jean-Pierre said.

Griner, the famous WNBA player, was arrested in February on drug charges and sentences to nine years in prison. Whelan, a corporate security executive, is currently serving a 16-year sentence for espionage charges that his family says are trumped up. The U.S. declared both to be wrongfully detained, a legal clarification that mobilizes federal resources to free Americans imprisoned abroad.

The talks between Washington and Moscow have been complicated by Russia's invasion of Ukraine.

There have been few public signs of progress since Secretary of State Antony Blinken, in a rare announcement in late July, revealed the U.S. had made the "substantial proposal" to secure the release of both Americans.

Sources told ABC News that offer included a prisoner swap that would exchange Viktor Bout -- a convicted Russian arms dealer currently serving a 25-year sentence in a federal penitentiary in Illinois -- for Griner and Whelan.

While U.S. officials say direct communication with the Kremlin continues at a regular clip, they acknowledge the slow pace is frustrating.

"Why this process has taken so long is a better question for Moscow," State Department spokesperson Ned Price said Thursday.

"I wouldn't characterize the process as stalled, he said. "It certainly hasn't moved with the speed we would like."

Some observers speculate Russia will demand parity, demanding two prisoners for the American detainees. Others within the State Department have questioned whether the Kremlin is negotiating in good faith and genuinely interested in reaching an agreement.

As talks continue behind the scenes, the Biden administration has bristled at any outside influence. After former New Mexico governor and hostage negotiator Bill Richardson traveled to Moscow this week, officials warned such interference could jeopardize the delicate diplomacy underway.

"Our message is that private citizens should not be in Moscow at all right now and that private citizens cannot negotiate on behalf of the United States government," National Security Council spokesperson John Kirby said on Wednesday.

Richardson became involved in Griner's case at her family's request back in May and over many years has been involved in multiple successful efforts to free detained Americans.

"Of course, families are perfectly free to engage in to consult with outside voices, with outside entities," Price said Wednesday. "But again, we want to make sure that any outside effort is fully and transparently coordinated with us."

Price said the U.S. embassy is Moscow had not been involved in Richardson's trip.

ABC News reached out to the Richardson Center for Global Engagement, but a spokesperson declined to comment or answer questions.

ABC News' Molly Nagle contributed to this report.