A government panel on Thursday essentially doubled its estimate of how much oil has been spewing from the out-of-control BP well, with the new calculation suggesting that an amount equivalent to the Exxon Valdez disaster could be flowing into the Gulf of Mexico every 8 to 10 days.

The new estimate is 25,000 to 30,000 barrels of oil a day. That range, still preliminary, is far above the previous estimate of 12,000 to 19,000 barrels a day.

These new calculations came as the public wrangling between BP and the White House was reaching new heights, with President Obama asking for a meeting with BP executives next week and his Congressional allies intensifying their pressure on the oil giant to withhold dividend payments to shareholders until it makes clear it can and will pay all its obligations from the spill.

The higher estimates will affect not only assessments of how much environmental damage the spill has done but also how much BP might eventually pay to clean up the mess — and they will most likely increase suspicion among skeptics about how honest and forthcoming the oil company has been throughout the catastrophe.