WASHINGTON -- Investigating the prostitution scandal at the Secret Service, the Homeland Security Department's inspector general uncovered a hotel record suggesting a member of President Barack Obama's team might have been involved, according to a summary of the case submitted to Congress. A senior administration official said the White House determined the record was false and that the person in question did nothing wrong.

The possibility of such an encounter raises the potential for fallout for the White House, which reviewed the matter and cleared its workers of wrongdoing. In a sign of campaign politics, Republican lawmakers questioned the credibility of the White House review, as Obama's team feared.

"I am troubled that the (inspector general's) findings reveal White House personnel may have been involved," Sen. Susan Collins, R-Maine, said in a statement. "The White House explicitly denied any involvement after its own investigation and now the IG is questioning that account. This raises concerns about the credibility of the White House investigation."

Sen. Chuck Grassley, R-Iowa, sent the White House a letter Thursday asking for more information about its internal review of the incident. Grassley also questioned whether the White House had any role in delaying the inspector general's report, which had been expected to be completed months ago.

The acting inspector general, Charles K. Edwards, said the employee-- described by

the administration as a volunteer, not a staff member -- "may have had contact with foreign nationals" and "may have been affiliated with the White House advance operation," according to a letter to lawmakers obtained by the AP. Edwards cited as evidence a hotel registry obtained by his investigators.

Edwards acknowledged that his investigators did not pursue information about the activities of the White House worker, who was not identified, or the actions of another U.S. military employee, because his report was intended to focus solely on employees at the Homeland Security Department. Edwards said his office "did not conduct any additional investigation into this finding and has made no determination related to these individuals because they are not DHS personnel."

Edwards also said that while the Secret Service employees "engaged in misconduct" Obama's security was never at risk.

The senior administration official told the AP that the hotel record Edwards cited in his letter to Congress was incorrect, and the person affiliated with the White House team did nothing improper. The official spoke on condition of anonymity to disclose details of a review that has not been made public and also spoke to quickly quash a potential controversy.

The Obama team member in question was a volunteer working as part of White House advance team that helped set up Obama's trip to Cartagena, Colombia, for a Latin America summit in April. The worker had his expenses paid but is not on the White House staff.

The official who spoke to the AP refused to name the White House advance team member.

The White House review found that a guest, perhaps a prostitute, had signed in to visit the same room assigned to that volunteer member of Obama's team. This occurred at the Hilton hotel where Obama would later stay during his visit.

But the review found that hotel log was false and that there was no other evidence to corroborate that the individual had received a visitor, the official said.