Republicans and Democrats have been at odds over whether to compel Cunningham to testify. In her memo, Harman accused Rep. Peter Hoekstra (R-Mich.), chairman of the committee, of backing out of an agreement to issue a subpoena.
"I strongly believe that we should compel his testimony," Harman wrote. "Given the scope of the damage he caused, I do not believe we should let Cunningham off the hook."
A GOP aide said Hoekstra intended to obtain testimony from Cunningham but thought that issuing a subpoena now would be counterproductive. The aide said Hoekstra had instead instructed the attorney leading the committee's investigation, Michael Stern, to negotiate with Cunningham's lawyers "to see if we can secure his testimony."
"We want to get answers from the man," the aide said.
A spokesman for Hoekstra, Jamal D. Ware, said the committee chairman could not comment on the matter, citing the agreement among members not to discuss the investigation publicly.
Cunningham's attorney, K. Lee Blalack II, has warned the committee that if Cunningham were subpoenaed, he would refuse to testify, citing the protection of the 5th Amendment.
In an Aug. 1 letter to the committee, Blalack noted that Cunningham was willing to cooperate and had turned over documents requested by the panel. But he said Cunningham would not testify unless he were granted immunity, or until his cooperation with federal prosecutors was completed.
Republicans and Democrats are divided over how much of the investigation's findings should be released. Senior aides say Stern has completed a classified report that is nearly 50 pages long, as well as a 20-page unclassified version.
In her memo, Harman said Democrats should push to have the full unclassified text released to the public.
"There is no reason that our committee should be able to 'bury' any unclassified facts about our committee's business, however unpleasant or embarrassing," Harman said.
Ware said: "Committee rules don't permit the discussion of internal committee business, even when it's unclassified."
Other Republican and Democratic members of the House Intelligence Committee did not respond to requests for comment.
