(CNN) – Rep. Michael Grimm, who on Monday voiced support for President Barack Obama's plan to strike Syria, stepped away from his endorsement on Thursday by claiming the president was backtracking on previously held postures toward the use of chemical weapons.
The Republican lawmaker, who represents parts of Staten Island, originally said on CNN's "The Situation Room" Monday that he would vote to support Obama's use of force in Syria, saying it would damage American credibility if President Bashar al-Assad wasn't punished for allegedly using sarin gas against his people.
"The president of the United States already committed us," he said Monday. "The president of the United States committed us when he drew the red line. So the idea that we should or we shouldn't strike, I think that ship sailed a long time ago if we want to keep the credibility of the United States."
But on Thursday, Grimm said he could no longer back Obama's plan for military strikes, arguing the president's statement this week that the "world set a red line," rather than himself, amounted to a reversal of policy.
"When I see the president backtracking on what he said, and what I was relying on to back him, that is obviously a big concern for me," Grimm told CNN chief domestic affairs correspondent Jessica Yellin on "The Situation Room."
Pressed on what had changed in Syria since Monday, Grimm claimed there was a growing global sense that Obama was being indecisive about military action.
"I think at this point the world is looking at the indecisiveness, they're looking at how the president has bungled this and now we can no longer get our credibility back," he said. "When I weigh everything - the extreme cost of war and the extreme cost of human life that could be the reality if we strike - we can no longer get our credibility back. I'm not sure what the end game is."
"The president and administration has failed to really explain exactly what the plan is, what the goal is and that's a big problem for me," he continued. "We have to know exactly what we're doing, how we're striking and to what end and we have failed to do that."
While those hang-ups were also true Monday, Grimm argued that too much time has passed since the chemical weapons attack for U.S. strikes to be effective.
"By the time the Congress actually votes on this, I don't think we can get our credibility back on this," he said.