WASHINGTON (AP) — The Biden administration has made a new and significant offer aimed at securing the release of American detainees Paul Whelan and Evan Gershkovich, but Russia has rejected the offer, the State Department said Tuesday.

Spokesman Matthew Miller did not reveal the details of the offer nor why Russia had turned it down, but the revelation of the proposal was a fresh indication that Washington is continuing to try to negotiate with Moscow to get both men home.

“This was a new proposal, in recent weeks. It was a significant proposal,” Miller said. “And it was rejected by the Russians but it does not, it will not deter us from continuing to do everything we can to try and bring both of them home.”

The U.S. government has declared both Whelan and Gershkovich to be wrongfully detained.

Whelan, a corporate security executive from Michigan, has been jailed in Russia since his December 2018 arrest on espionage-related charges that both he and the U.S. government dispute. He was sentenced to 16 years in prison,

Gershkovich, a Wall Street Journal reporter, was detained in March while on a reporting trip to the Russian city of Yekaterinburg, about 2,000 kilometers (1,200 miles) east of Moscow.

Gershkovich and the Journal deny the allegations, and Russian authorities haven’t detailed any evidence to support the espionage charges. A Russian court last week extended the detention until Jan. 30.

“They never should have been arrested in the first place. They should be released immediately,” Miller said. “But we have made a number of proposals and including a substantial one in recent weeks and we will continue to work every day to bring Evan and Paul Whelan home. There is no prior higher priority for the Secretary of State. There is no higher priority for the president.”

In July 2022, Secretary of State Antony Blinken revealed that the U.S. had made a substantial proposal to Moscow to get home WNBA star Brittney Griner and Whelan. Griner was ultimately released in December in a prisoner swap with notorious Russian arms trafficker Viktor Bout, but Whelan was not part of the deal.