Senior White House adviser Kellyanne Conway has suggested that former president Barack Obama used microwaves to spy on President Trump.
In an interview with the Bergen County Record, Ms Conway had said that people should think beyond wiretapping in terms of monitoring individuals, saying "there are many ways to surveil each other."
Her remarks came after a congressional aide's statement over the weekend saying the House intelligence committee had asked the Trump administration to provide by today evidence that Donald Trump's phones at Trump Tower in New York were tapped.
Mr Trump has alleged that then-President Barack Obama ordered the surveillance - a charge that Mr Obama has denied.
Ms Conway told the Bergen County Record, "You can surveil someone through their phones, certainly through their television sets, microwaves which turn into cameras - any number of ways."
Conway told ABC's Good Morning America that "of course I have no evidence for this," saying that's why there's a need for an investigation.
"I wasn't making a suggestion about Trump Tower," she told the network. She said she was answering a question about surveillance "generally," and without specific reference to the current controversy.