The former secretary of homeland security Janet Napolitano on Sunday added her voice to opposition to clemency or a plea deal being offered to Edward Snowden, the former National Security Agency contractor who leaked thousands of documents on the agency's surveillance operations to media outlets including the Guardian.

Also on Sunday, the Republican senator Rand Paul, who has advocated a softer line on Snowden than many in his party, said he thought the whistleblower “probably would come home for a few years in prison”.

Earlier this week, the New York Times published an editorial calling for Snowden to be allowed to return to the United States. He is currently in Russia, where he was granted one year's asylum.

The editorial, entitled “Edward Snowden, Whistle-Blower”, called for the offer of “a plea bargain or some form of clemency that would allow him to return home” and said: “Mr Snowden is now … on the run from American charges of espionage and theft, and he faces the prospect of spending the rest of his life looking over his shoulder.”

"From where I sit today, I would not put clemency on the table at all," said Napolitano, who was homeland security secretary from 2009 to September last year, in an interview with NBC's Meet the Press. She added: "I think Snowden has exacted quite a bit of damage and did it in a way that violated that law. The damage we'll see now and we'll see it for years to come."

The notion of an amnesty for Snowden, in return for the return of documents in his possession, was raised last month by Richard Ledgett, the NSA official in charge of assessing the Snowden leaks and a contender to become the agency's top civilian. Speaking to CBS News, Ledgett said: “My personal view is, yes, it’s worth having a conversation about. I would need assurances that the remainder of the data could be secured, and my bar for those assurances would be very high. It would be more than just an assertion on his part.”

The White House rejected the idea, spokesman Jay Carney telling reporters: “Mr Snowden has been accused of leaking classified information and he faces felony charges in the US. He should be returned to the United States as soon as possible, where he will be accorded full due process.”

Appearing on Sunday on ABC's This Week, Senator Paul was also asked about clemency for Snowden. Referring to remarks he made suggesting Snowden and the director of national intelligence, James Clapper, should share a prison cell, Paul said: “I don't think Edward Snowden deserves the death penalty or life in prison – that's why he fled. He probably would come home for a few years in prison, which would be not unlike what James Clapper should get for lying to Congress.”

Clapper has been accused of lying to Congress after denying in a Senate hearing last year that the NSA was collecting data on millions of Americans. On Saturday the general counsel to the Office of National Intelligence, Robert Letts, wrote to the New York Times to deny that allegation.

On Sunday, Paul did not call for clemency or leniency for Snowden, but he did hint that his acts should be put into context. "What history will show is that he revealed great abuses of our government and our intelligence community," he said.