The Trump administration admitted it's worried that a nuclear deal with Iran is increasingly unlikely, the Wall Street Journal reported.

Senior U.S. officials told The Wall Street Journal on Friday that a nuclear deal with Iran is "growing increasingly unlikely" in a "rare acknowledgment."

A deal to limit Iran's nuclear capacity was one of Trump's "core foreign-policy goals," the Journal noted. However, the senior officials who spoke to the Journal are expecting Iran to release a statement declaring that it will stop firing at ships crossing the Strait of Hormuz and leave it open.

"One of the officials suggested there would be serious consequences if such a promise isn't made by Saturday," the Journal wrote, referring to the Strait of Hormuz statement. "Others didn't suggest there was a firm deadline."

The Journal noted that Trump told reporters earlier this week that Iran will "never build a nuclear weapon under our deal, but I don't know if we're going to have a deal."

Sources told the Journal that a nuclear deal wouldn't be possible unless Iran hands over control of its buried enriched uranium, and the U.S. has "low-cost military options to block access to the nuclear material forever."

Under the current memorandum of understanding, the U.S. and Iran have 60 days to reach a final nuclear agreement, which could be extended, the Journal added.

"Iran made no explicit promises to scale back its nuclear program in the interim deal," the Journal wrote. "But it did commit to the two sides reaching a satisfactory solution for handling Iran's existing stockpile of highly enriched uranium."