"I think once Russia has made all the gains that they believe are sufficient for them to have the outcome they have in Syria, then I think they will cease fire," Corker stated.
The chairman argued that US Secretary John Kerry "has no leverage" in carrying out the ceasefire talks.
"Because Russia doesn’t believe the United States, under this president [Barack Obama], is going to take any action," Corker said.
On Monday, the United States and Russia, co-chairs of the International Syria Support Group, announced they had reached an agreement to halt hostilities among the warring sides in Syria.
The agreement excludes terrorist groups like Daesh, also known as ISIL, and the Nusra Front; seeks to ensure humanitarian access to besieged cities; and advances a political resolution to the crisis.
Corker further noted that Russia "consolidated their gains" and "made additional gains" in Syria over recent weeks.
The ISSG was initially working to implement a cessation of hostilities at the beginning of February, but lacked sufficient buy in from all the stakeholders.
Russia committed its armed forces to combat the terrorist threat in Syria in September 2015 at the request of the Syrian President Bashar Assad. Over recent months, the rate of Russian airstrikes against terrorist targets inside Syria have exceeded those of the US-led coalition against Daesh.
