The Trump administration has lifted sanctions on three firms linked to Russian oligarch Oleg Deripaska, an ally of President Vladimir Putin.
Curbs on aluminium giant US Rusal, En+ Group and JSC EuroSibEnergo were lifted after Mr Deripaska ceded control.
The oligarch has been linked to the probe into alleged Russian interference in US elections, and Democrats wanted the sanctions to continue.
But the Treasury Department said curbs on oligarch himself remained in force.
The companies were blacklisted last April when the Trump administration targeted people and businesses it said had profited from a Russian state engaged in "malign activities" around the world.
That included Russia's alleged meddling in the 2016 US presidential election, as well as international cyber attacks.
But earlier this month, Republicans in the US Senate blocked an effort to continue the sanctions against Rusal, the world's second largest aluminium firm and other Deripaska-linked firms.
They and the Trump administration argued the curbs could have an impact on the global aluminium industry. They also said Mr Deripaska had lowered his stakes in the firms so that he no longer controlled them, a sign the sanctions were working.