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The scandal involving at least 11 U.S. Secret Service personnel that began Wednesday in Colombia could be much larger than initially reported, a Republican lawmaker said Sunday.

House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.), whose panel maintains jurisdiction over all federal agencies, said he had reason to believe that more than 11 Secret Service personnel were involved but never specifically explained why.

“We think the number might be higher and we’re asking for the exact amount of all the people who, quote, were involved,” Issa said on CBS’s “Face the Nation.” “But this kind of a breach is a breach in the federal workforces’ most elite protective unit, and they don’t just protect the president, of course; they protect the Cabinet members, the vice president, the first family, candidates. So when you look at this, you realize if you can have this kind of breakdown, one that could lead to blackmail . . . then we’ve got to ask: Where are the systems in place to prevent this in the future?”

“The reason the investigation will not be about the 11 to 20 or more involved, it’ll be about how this happened and how often has this happened before: Things like this don’t happen once if they didn’t happen before.”

At least 11 Secret Service personnel and five military officials are known to be involved in the situation, according to Secret Service and military spokespeople. Issa did not clarify on CBS how as many as 20 could be involved.

But — as Issa has been known to do in the wake of a fresh scandal — the California Republican openly questioned whether similar incidents involving agents had occurred before, noting that Secret Service agents assigned to overseas trips customarily hold “wheels-up parties” once the president or other protectees leave an area on their return flight to Washington.

Issa also told CBS that his committee would further investigate the incident, meaning at least two House committees are now probing the matter.

On Saturday, Rep. Peter T. King (R-N.Y.), chairman of the House Homeland Security Committee, said his staff also will conduct a preliminary investigation.

The possibility of another congressional inquiry into a brewing scandal involving a federal agency may yet again pit Issa against fellow GOP committee chairmen who also have oversight of the Secret Service.

Some Republicans have griped privately that Issa moved quickly to step out in front of the investigation into lavish spending on conferences held by the General Services Administration. Issa’s committee is slated to hear testimony Monday afternoon from current and former GSA officials, ahead of similar hearings later in the week by House and Senate committees.

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