Steve Wereley, an associate professor at Purdue University, believes it could be much larger, a staggering 70,000 barrels per day.
"I know how much is coming out could potentially be important for scaling the cleanup operation as well as what technologies might be applicable in plugging the leak," Wereley said.
President Obama argued today that the precise size the leak is in many ways irrelevant.
"Our mobilization and response efforts have always been geared towards the possibility of a catastrophic event," he said, addressing the various estimates. "There's oil leaking and we need to stop it, and stop it as soon as possible."
In response to the president's remarks, Tony Hayward, BP's CEO, thanked the administration for its "engagement" in the response effort and said the company understands and shares Obama's "sense of urgency over the length of time this complex task is taking."
Overnight, BP, the damaged well's owner, began its latest attempt to plug the leak using deep-sea robots to try and insert a small pipe to siphon the oil to a ship on the surface. Adm. Allen said today workers are also preparing to make a second attempt at capping the flow with a special dome.
BP has committed to pay for the entire response effort and compensate affected residents. It says it has already spent $450 million on the cleanup. The company made a $5.6 billion profit in the first three months of this year, or $62 million per day.
The federal government's role in the disaster also has not escaped Obama's scrutiny, and today he endorsed a recent Interior Department decision to split the function of the Minerals Management Service so that one agency is not collecting royalties from oil companies while it also enforces safety rules.
Interior Department Secretary Ken Salazar is conducting a review of the Service and ordered new inspections of deep-water oil operations. The issuance of new permits to drill has also been put on hold.
"For too long, for a decade or more, there has been a cozy relationship between the oil companies and the federal agency that permits them to drill," he said. "That cannot and will not happen anymore."
But the ongoing disaster in the Gulf has not changed the administration's decision to keep domestic oil drilling as part of its broader energy strategy, despite speculation that the president might have to reverse course.
"Domestic well drilling continues to be one part of an overall energy strategy that now includes more clean, renewable energy and energy efficiency than in any other time in our history," Obama said. "But it's absolutely essential going forward we put in place every necessary safeguard and protection so that a tragedy like this oil spill does not happen again."
More Americans approve of the administration's handling of the Gulf oil spill than don't, 43 percent to 33 percent, according to the latest Associated Press poll.
ABC News' Jeffrey Kofman, Darin Byrne and Kate McCarthy contributed to this report.