Local law enforcement officials also welcome the teams.

“We’ve found a lot of value in having these high-visibility security details,” said John Siqveland, a spokesman for Metro Transit, which operates buses and trains Minneapolis-St. Paul. He said that local transit police have worked with VIPR teams on security patrols on the Metro rail line, which serves the Minnesota Vikings stadium, the Mall of America and the airport.

Kimberly Woods, a spokeswoman for Amtrak, said the railroad has had good experiences with VIPR team members who work with the Amtrak police on random bag inspections during high-travel times. “They supplement our security measures,” she said.

But elsewhere, experiences with the teams have not been as positive.

In 2011, the VIPR teams were criticized for screening and patting down people after they got off an Amtrak train in Savannah, Ga. As a result, the Amtrak police chief briefly banned the teams from the railroad’s property, saying the searches were illegal.

In April 2012, during a joint operation with the Houston police and the local transit police, people boarding and leaving city buses complained that T.S.A. officers were stopping them and searching their bags. (Local law enforcement denied that the bags were searched.)

The operation resulted in several arrests by the local transit police, mostly for passengers with warrants for prostitution and minor drug possession. Afterward, dozens of angry residents packed a public meeting with Houston transit officials to object to what they saw as an unnecessary intrusion by the T.S.A.

“It was an incredible waste of taxpayers’ money,” said Robert Fickman, a local defense lawyer who attended the meeting. “Did we need to have T.S.A. in here for a couple of minor busts?”

Representative Bennie Thompson, Democrat of Mississippi and ranking member on the House Homeland Security Committee, which has oversight of the T.S.A., said he generally supports the VIPR teams but remains concerned about the warrantless searches and the use of behavior detection officers to profile individuals in crowds.