Strzok is set to testify before the Judiciary Committee and the House Oversight & Government Reform Committee on Thursday.
Page was subpoenaed to provide a deposition behind closed doors on Wednesday, but she didn't appear under Jeffress's advice.
'Congressional subpoenas for testimony are not optional, ' he said.
"There is no basis for claims that Lisa has anything to hide or is unwilling to testify", she said, adding that the Oversight and Judiciary committees' "bullying tactics here are unnecessary".
"She could go to jail if they really want to press it for blowing off", Napolitano said. But a subpoena to testify before Congress is not optional. "It's mandatory. She needs to comply", Ryan said after a regular House GOP conference meeting.
Mr. Strzok, who was briefly part of Mr. Mueller's team, made national headlines late a year ago when texts sent to his lover, former Federal Bureau of Investigation attorney Lisa Page, were made public.
During 2016, Page and Strzok were having an affair while they were both involved in the politically charged investigation of Clinton, Trump's Democratic election rival, for misuse of classified materials on her private email server. "In fact, Lisa and I went to the Federal Bureau of Investigation today to review the materials that were previously produced to Congress relating to her proposed interview, but after waiting for more than three hours, we were not provided with any documents".More news: Thailand cave rescue: First pics of boys in hospital
He warned of unspecified action by the committees to force her to testify, leaving Page at potential risk of a contempt of Congress citation.
In a letter to the committees' chairmen, they said an inquiry originally billed as reviewing the investigation into Democrat Hillary Clinton's use of a private email server "has morphed into a partisan, abusive, and improper inquisition of Special Counsel Mueller's investigation of President Trump's campaign and its connections to Russian Federation".
Trump is 'not ever going to become president, right?
'I am on Air Force One flying to North Atlantic Treaty Organisation and hear reports that the Federal Bureau of Investigation lovers, Peter Strzok and Lisa Page are getting cold feet on testifying about the Rigged Witch Hunt headed by 13 Angry Democrats and people that worked for Obama for 8 years.
"The Committees would be asking Lisa about materials she has not yet been shown", the lawyer continued. What are you hiding, Miss Page?
Strzok was removed from Mueller's team when the texts were discovered past year. Trump wrote that Page is an "Ex-FBI LAYER", which is not a thing.