Published: Jun 06, 2010 8:27 PM EDT
Updated: Jun 06, 2010 5:29 PM EDT

WASHINGTON (AP) - The government's point man on the Gulf of Mexico oil spill says the catastrophe will persist "well into the fall."
      
Coast Guard Adm. Thad Allen said Sunday on CBS' "Face the Nation" that the spill will not be contained until the leak at the bottom of the Gulf is fully plugged.
      
He says that even after that, "there will be oil out there for months to come."
      
The leak began nearly seven weeks ago after a BP rig exploded and ruptured a wellhead, creating what has become the nation's largest oil spill. A containment device began capturing some of the oil late last week and is slowly siphoning off the flow.
      
Allen tells "Fox News Sunday" that he doesn't "want to create any undue encouragement" on the effectiveness of the device. He says the government needs "to underpromise and overdeliver" as it works with BP to stem the flow of oil.