WASHINGTON (Reuters) - A congressional panel has been asked to postpone a closed door deposition with a former Department of Homeland Security (DHS) intelligence chief because of delays in obtaining access to classified records and approval of security clearances for his lawyers. But Adam Schiff, the Democrat who chairs the House of Representatives Intelligence Committee, said on Friday his panel was "rejecting the Department’s attempt to limit the scope of its investigation" into the DHS intelligence office, which would-be witness Brian Murphy formerly headed. Murphy said in a whistleblower complaint on Sept. 8 that President Donald Trump's acting DHS chief...