President Joe Biden this weekend said he is doing everything in his power to release Wall Street Journal reporter Evan Gershkovich from Russian custody, as friends and colleagues continue to send letters of support to keep his spirits up.

“We’re working every day to secure his release, looking at opportunities and tools to bring him home,” Biden told the audience, which included Gershkovich’s parents, at the White House Correspondents’ Dinner on Saturday. “We keep the faith.”

Gershkovich, who has been designated as wrongfully detained by the U.S. State Department, was arrested by Russia’s Federal Security Service in Yekaterinburg in late March, the first U.S. journalist to be detained on spying charges since the Cold War.

Gershkovich, the Journal and the U.S. have all denied the charges.

Last month, a judge denied Gershkovich’s request to be released from pretrial detention, meaning he will remain there at least until May 29.

Russia has also blocked a request for a May 11 consular visit to the reporter in retaliation for the U.S. blocking Russian journalists from joining Russian Foreign Minister Sergey Lavrov on his trip to the United Nations in New York.

“Other possible retaliatory measures, about which the U.S. side will be duly notified, are being considered,” the Russian Foreign Ministry said Friday.

Meanwhile, Gershkovich’s friends and family have set up a campaign to send him letters of support. A group of volunteers in Russia are tasked with translating the letters to Russian, as required by the country’s law, and mailing them to Lefortovo prison where he is being held.

“I am humbled and deeply touched by all the letters I received. I’ve read each one carefully, with gratitude,” Gershkovich said in a statement shared through his lawyers Thursday.

“One of the best ways to support him is to make sure that he knows that he is the center of everybody’s attention worldwide right now,” Polina Ivanova, a onetime Financial Times employee in Russia and a friend of Gershkovich who helps to organize the letters campaign, told NBC News.

Last week, the Biden administration imposed a new set of sanctions meant to deter and punish those who wrongfully detain Americans and take them as hostages.