Obama, the front-runner for the Democratic presidential nomination, wrote to Secretary of Veterans Affairs James Peake, urging him to look into a Washington Post report that Norma Perez -- a psychologist at the Department of Veterans Affairs' Olin E. Teague Veterans' Center in Temple, Texas -- urged staff members to "consider a diagnosis of adjustment disorder" rather than post-traumatic stress disorder for patients there.

The report was based largely on an e-mail obtained by a veterans' advocacy group.

"Given that we are having more and more compensation seeking veterans, I'd like to suggest that you refrain from giving a diagnosis of PTSD straight out," The Post quotes the March 20 e-mail as saying.

Veterans diagnosed with PTSD can be eligible for compensation of up to $2,527 per month. Bush administration officials said there was no effort to underdiagnose post-traumatic stress disorder to save money.

Peake issued a statement denouncing Perez's e-mail as "inappropriate" and maintained that it doesn't reflect Veteran's Administration policy. The e-mail has been "repudiated at the highest level of our healthcare organization," he told the Post.

In his letter to Peake, Obama said an investigation should determine whether Perez sent the e-mail "at the urging of her superiors," and whether staff members at the Teague Center followed her suggestion.

He also said investigators should determine whether officials at other veterans centers "have given some similar admonitions."