"I think that the fact that it's taken this White House and this president so long to get a clear and concise policy on Syria has ... left us with the worst possible scenario right now," Rubio said during his appearance on ABC's "This Week" Sunday.
Rubio said the administration waited too long to start working with elements on the ground in Syria.
"It behooved us to kind of identify whether there were any elements there within Syria fighting against [Bashar] Assad that we could work with, reasonable people that wouldn't carry out human rights violations, and could be part of building a new Syria. We failed to do that. This president failed to do that," Rubio said.
His comments come after Obama approved sending arms to the country's rebels this week, after determining that the Syrian government has used chemical weapons.
Rubio said the U.S. government should continue to search for elements on the ground that that it can work with.
"I think we should continue to search to see if there are any elements fighting against Assad that are reasonable, that we can work with, that will respect human rights and hopefully build a new Syria," he said.
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