A plot to harm Pope Francis during his U.S. tour has been foiled by authorities, House Homeland Security Committee Chairman Mike McCaul told ABC's "This Week" on Sunday. (WUSA9)

American authorities are “monitoring very closely” any potential threats against Pope Francis and have already “disrupted one particular case” ahead of the pope’s visit to the United States, House Homeland Security Committee Chairman Michael McCaul said Sunday on ABC’s “This Week.

Rep. McCaul (R-Tex.), when asked how he felt about security preparations ahead of the papal visit next week, said he was “concerned” and has been briefed by the Secret Service on the matter.

“The pope is a very — I’m Catholic, by the way — he is a very passionate man,” McCaul said. “He likes to get out with the people. And with that comes a large security risk.”

The pope’s upcoming trip to the United States has prompted a massive security operation in the three cities he will visit — New York, Washington and Philadelphia. In Washington, several major roadways will close for long periods during the three days that Francis is in town, and District officials are urging anyone who can to telecommute for the duration.

“We are monitoring very closely threats against the pope as he comes in to the United States,” McCaul said on “This Week.” “We have disrupted one particular case in particular. But as that date approaches, I think we’re all very . . . vigilant to protect him as he comes into the United States.”

It was not clear whether the “disrupted” case McCaul mentioned was a threat against the pope, or a reference to a recent arrest in Florida of a man who allegedly was planning an attack at a Sept. 11 memorial in Kansas City. “This Week” host Martha Raddatz mentioned that case in her question to the congressman.

Asked to clarify the comment, Susan Phalen, a spokeswoman for McCaul, said Sunday evening: “We have nothing further to add at this time.”

Here’s the full exchange from “This Week”:

RADDATZ: And Chairman McCaul, if you would quickly, we of course have the pope coming soon. There’s always concern about lone-wolf attacks. I think someone was arrested this week in Florida, a suspect, sympathizer with ISIS. Do you feel secure about the pope coming in to America?

MCCAUL: I’m concerned. I was briefed by the Secret Service in a classified setting. The pope is a very — I’m Catholic, by the way — he is a very passionate man. He likes to get out with the people. And with that comes a large security risk.

We are monitoring very closely threats against the pope as he comes in to the United States. We have disrupted one particular case in particular.

But as that date approaches, I think we’re all very — be very vigilant to protect him as he comes into the United States.

Those in charge of Pope Francis’s security during his papal trips must contend with the pontiff’s well-known preference to as much as possible be open to those who want to see him.

[This popemobile parade is probably your best bet at seeing Pope Francis in D.C.]

Since becoming pope, for instance, Francis has used partially or fully open-air Popemobiles to drive through crowds, as opposed to the closed, bulletproof version of the papal vehicle favored after a 1981 assassination attempt on John Paul II.

Francis has previously said that he feels as if he’s trapped in a “sardine can” in the fully closed Popemobile.

In January, the Vatican’s press office dismissed reports that the Vatican was under threat from Islamic State terrorists. But Domenico Giani, the head of the Vatican City’s police force, said a couple of months later that “the threat exists,” adding that “we know of no plan for an attack against the Vatican or the Holy Father.”

Mike DeBonis contributed to this report, which has been updated.