House intelligence committee sources say career officials at the National Security Council are slow-walking the delivery of subpoenaed records on former National Security Adviser Susan E. Rice’s handling of classified information and the “unmasking” of Trump campaign workers — material from the Russian hacking probe that middle-level NSC managers claim was transferred to President Obama’s library and could “remain closed to the public for five years.”

One source, speaking only on the condition of anonymity, called the transfer curious and appeared to reflect an effort by former administration officials to obscure evidence on whether Ms. Rice and other top officials in the Obama White House illegally tried to identify which Trump campaign and transition aides had been caught up in the U.S. intelligence intercepts of Russian interference in the presidential race.

The two high-level intelligence committee sources told The Washington Times that they are confident the panel’s investigators, despite the delays, will eventually get their hands on the records shipped to a heavily secure archive for Mr. Obama’s yet-to-be-built presidential library.