The former acting U.S. attorney general's testimony will reveal "who knew what when" about Flynn's Russia contacts, says Senator Feinstein.
ABC News said the laptop contained floor plans for Trump Tower, details on the criminal investigation of Hillary Clinton's private email server and other national security information.
It was the second request for Trump's returns by Senate Democrats in as many weeks, part of a Democratic campaign to pressure Republicans in Congress into obtaining the documents.
Trump's plans may violate international law and spark an intelligence rift.
Trump's national security transition has been more chaotic than others in recent memory, with important positions unfilled and many of his people less able, or willing, to engage on substance, U.S. officials said.
Meanwhile, Donald Trump has been selected as "Time" magazine's Person of the Year.
Arizona is the biggest prize for both parties Tuesday night.
Residents in three Western states are casting their picks as national security once again is a hot-button issue.
Vigorous independent oversight of counterterrorism activities sacrifices neither liberty nor security.
The bill will be finished in coming weeks, a top Pentagon official said Tuesday.
Obama has provided regular, public updates about national security since the December 2 attack in San Bernardino.
The president urged other countries to join in the fight against the militant group.
The Texas senator dubs the end of Obama administration as "proof there is a God" and compares "radical Islamic terrorism" to Communism.
The president says the nation is being protected and urges Americans to enjoy Thanksgiving.
The New Jersey governor touts his September 11 bona fides.