So-called "lone wolf" terrorist attacks are the greatest threat to New York City, which faces a "greater likelihood of attack than we have seen in years," NYPD Commissioner William Bratton is set to say in prepared remarks Tuesday morning before a congressional hearing in lower Manhattan.

"In many respects, we currently face a greater likelihood of attack than we have seen in years," a copy of Bratton's statement says. "With regard to crime, we just experienced the safest summer in 25 years, with murders and shootings at modern lows. But with regard to the current terror threat environment, we now face multiple hazards -- 'known wolves and lone wolves.'"

The House Committee on Homeland Security field hearing is scheduled to take place Tuesday morning and will also feature former New York City Mayor Rudy Giuliani as a speaker.

The hearing is being held at the 9/11 Memorial and Museum -- just days before Friday's 14th anniversary of the attacks. It is the first time a congressional hearing is being held at the site, officials said.

Committee chairman Rep. Michael McCaul (R-Texas) called it a "historic" hearing.

Among the members of the Homeland Security committee are Rep. Peter King (R-Seaford) and Rep. Kathleen Rice (D-Garden City).