The Treasury Department's inspector general has begun an informal inquiry into whether the department's representative on the Air Transportation Stabilization Board was pressured to change his vote rejecting a loan guarantee request from United Airlines Inc., a spokesperson for the Treasury's inspector general's office said yesterday.

Last week, the ATSB turned down United's $1.6 billion application, with two of three board members opposing the request. Treasury Undersecretary Brian C. Roseboro voted against United's bid, but the department later said it would reconsider another application from the airline.

After the vote, Sen. Peter Fitzgerald (R-Ill.) wrote to Dennis S. Schindel, the Treasury Department's acting inspector general, encouraging him to look into "whether any inappropriate political pressure or intimidation has been or is being applied to Mr. Roseboro to change his vote."

Richard Delmar, a spokesman for the independent inspector general's office, said Fitzgerald's letter triggered the inquiry. "We're going to do a preliminary inquiry into the questions the senator raised in his letter," he said. No time frame has been determined, but Delmar said the investigation would be completed "expediently."

House Speaker J. Dennis Hastert (R-Ill.), whose district includes United's headquarters in Elk Grove, Ill., has been an advocate for the airline.

Treasury Department spokesman Rob Nichols said that Hastert has contacted department officials but that such lobbying was "normal." Other members of Congress have lobbied on behalf of carriers that applied for the loan guarantees, he said.

The $10 billion loan guarantee program was created by Congress to help stabilize the airline industry following the Sept. 11, 2001, terrorist attacks.

"The fact a legislator contacted the administration on behalf of an issue that affects their constituents is normal," Nichols said. "We have made a judgment based simply on its merits. And that's how we would look at future applications."

ATSB Chairman Edward M. Gramlich, a Federal Reserve governor, voted against United's application while Jeffrey N. Shane, the Transportation Department's undersecretary for policy, voted to defer the decision for a week pending further information.

United, a unit of UAL Corp., resubmitted its application Tuesday, reducing its aid request to $1.1 billion.

Treasury Undersecretary Brian C. Roseboro voted against a federal loan guarantee for United Airlines.