Democrats and Republicans are still fighting over how to implement fresh sanctions against Russia over alleged interference into the 2016 US election.
The most recent setback has come from Democratic opposition to a change that would limit the minority's ability to force a vote on a resolution of disapproval should the Trump administration decide to reverse sanctions.
As it stands, only the majority party would be able to bring in a resolution of disapproval, which would currently enable Republicans to defend Trump.
Sen. Bob Corker (R-Tenn.) said: "This is all doing nothing but helping Russia. Every day that goes by ... mischief can happen, and I think we really could have passed it the week before the [July Fourth] recess."
It is hoped that a breakthrough can be reached soon, with Democrats hoping to water down the language enough for them to be able to pass it.
Congress is keen to take a stronger line against Russia despite Trump pushing for a warmer relationship.
Russia has been contemplating its own new wave of counter-sanctions specifically aimed at the ones that Barack Obama brought in back in December 2016.
Around 30 US diplomats could be expelled from Russia. Intelligence compounds and offices may ALSO be closed.
It is thought that Russia could also seize a US government dacha at Serebryany Bor, northwest of Moscow, as well as a US warehouse in the capital.
Later this month, a meeting will take place between the Russian Deputy Foreign Minister Sergei Ryabkov and US Under Secretary of State Thomas Shannon, with the hope of reaching a compromise.