Eliza Collins, and Kevin Johnson

USA TODAY

WASHINGTON — Russian government hackers "curtailed'' their cyber espionage against U.S., political institutions after the Obama administration formally blamed the nation last month for breaching the computer systems of the Democratic National Committee and other entities, Director of National Intelligence James Clapper told a House panel Thursday.

"That activity seemed to have curtailed,'' Clapper told the House Intelligence Committee. "I can't say what the impact of a new (Trump) administration will have on Russian behavior.''

The previous breaches and recent scanning of some states' voter registration data bases prompted intelligence authorities to ramp-up cyber defenses in advance of the general election earlier this month. Though no major incidents were reported.

Asked at one point during Thursday's hearing whether any information stolen in the Russian breaches was provided to U.S., persons, Clapper declined to answer, saying any response should be deferred to a classified session of the panel.

At the start of the open hearing, Clapper announced that he had submitted his long-expected resignation to President Obama Wednesday night.

The director, who has overseen the nation's vast intelligence operation since 2010, said he "felt pretty good'' and that his wife was happy that his tenure would be up in just more than two months.

"I've got 64 days left,'' Clapper told the panel. "I would have a hard time with my wife for any time past that.''

While Clapper is the first intelligence official to acknowledge his departure at the end of the Obama administration, others, including CIA Director John Brennan, are set to follow, as President-elect Donald Trump weighs his own roster of candidates for nomination to sensitive cabinet posts.

A retired Air Force lieutenant general, Clapper was the director of the Defense Intelligence Agency in the Clinton administration. The 75-year-old Clapper was also head of the National Geospatial-Intelligence Agency between 2001 and 2006.

Clapper, making what is likely to be his last appearance before the committee, cataloged a list of daunting threats facing the country, including cyber warfare waged by other nations. He also called attention to the persistent domestic security challenge posed by the largely unknown.

"I will leave this job concerned about so-called lone wolves and homegrown violent extremists,'' Clapper said.

U.S. intelligence: Hackers tried to spy on 2016 candidates