WASHINGTON – President Barack Obama blocked large pay raises slated for tens of thousands of federal employees Monday, overriding statutory formulas to hold pay increases to 2% in 2010.

Invoking the "national emergency" declared after the Sept. 11, 2001, terrorist attacks, the president said in a letter to House Speaker Nancy Pelosi that under pay formulas set in 1990, federal employees with pay levels set according to comparable local wages are set for average pay increases of 18.9%.

White House officials say the declaration was routine. Ever since Congress passed the Federal Employees Pay Comparability Act in 1990, presidents have been invoking the emergency clause to hold down pay increases due under the formula that mandates wages comparable to local pay levels.

That has created a yawning gulf. If Mr. Obama did nothing, the comparability formula would dictate a 16.5% pay increase, on top of the 2.4% cost of living increase.

That would be a $22.6 billion hit to the ailing federal budget in 2010. Cost of living adjustments alone were to boost pay by 2.4% for most federal employees.