The United States allowed a sanctions waiver permitting purchases of Russian oil to expire on Saturday, following calls from Democratic senators to let the exemption lapse.

Sens. Elizabeth Warren of Massachusetts and Jeanne Shaheen of New Hampshire had urged the Trump administration on Friday not to extend the waiver, which was set to expire just after midnight on Saturday. The waiver had provided temporary relief from sanctions that restricted oil purchases from Russia.

"Tonight, when the current license for Russian oil expires, it should not be renewed," Shaheen stated in her Friday appeal to the administration.

The expiration comes amid what Bloomberg characterized as tight market conditions in the global oil sector. The waiver had allowed certain transactions involving Russian oil to proceed despite broader sanctions frameworks targeting Russia.

The decision to allow the waiver to expire represents a hardening of the U.S. sanctions posture toward Russian energy exports. The move aligns with the senators' position that exemptions from Russian oil sanctions should not be extended.