US President Joe Biden and Vice President Kamala Harris spoke with the wife of American basketball star Brittney Griner, who has been detained in Russia since February, the White House said on Wednesday.
The White House is facing increasing pressure from athletes and others to secure the two-time Olympic gold medallist's release.
"The president called Cherelle [Griner] to reassure her that he is working to secure Brittney’s release as soon as possible, as well as the release of Paul Whelan and other US nationals who are wrongfully detained or held hostage in Russia and around the world," the White House said.
"The president offered his support to Cherelle and Brittney’s family, and he committed to ensuring they are provided with all possible assistance while his administration pursues every avenue to bring Brittney home."
Griner, who was detained at a Moscow airport in February, was formally told last week that she had been charged with intentionally transporting drugs after cannabis vape oil was allegedly found in her bags.
The judge set her next hearing for Thursday.
A Russian judge said the basketball star may appeal or ask for clemency when a verdict is delivered.
The White House also confirmed that Mr Biden read the letter Griner sent to him this week, in which she pressed him to fight for her and other Americans detained abroad.
Cherelle Griner has also publicly advocated for her wife's release, and the Rev Al Sharpton urged the White House to arrange a visit for him and other faith leaders to visit the detained basketball star.
"It's my intention to be in Russia next week, and I hope the White House will help to make it possible for me to do a clergy visit to … let her know that he family and everyone is concerned about her and to pray with her," Mr Sharpton told NBC.