Text messages between former FBI officials Peter Strzok and Lisa Page indicate they discussed using briefings to the Trump team after the 2016 election to identify people they could "develop for potential relationships," track lines of questioning and "assess" changes in "demeanor" – language one GOP lawmaker called “more evidence” of irregular conduct in the original Russia probe.

Fox News has learned the texts, initially released in 2018 by a Senate committee, are under renewed scrutiny, with GOP Sens. Chuck Grassley and Homeland Security Committee chair Ron Johnson sending a letter Thursday night to Attorney General Bill Barr pushing for more information on the matter.

"Any improper FBI surveillance activities that were conducted before or after the 2016 election must be brought to light and properly addressed," the senators wrote.

President Trump, speaking to Fox News' "Hannity" Thursday night, responded to this report by unloading on Strzok and Page.

"They were trying to infiltrate the administration," Trump told Sean Hannity. "Really, it's a coup. It's spying. It's hard to believe in this country we would have had that." Trump called the news "very disconcerting," and emphasized that the Justice Department's watchdog previously faulted Strzok's communications with Page.

The text messages begin on the evening of Nov. 17 -- nine days after the election. The string discusses an email and briefing to "Pence," presumably Vice President-elect Mike Pence – and appears to refer to another upcoming briefing.

The messages showed Strzok and Page debating staffing for the upcoming briefing and whether it would make sense to stay with the same agent or send a different one. It is unclear from the texts whether these were part of the formal transition-period briefings between outgoing or incoming administrations or routine intelligence briefings.

'Outbox' refers to messages sent by Lisa Page. 'Inbox' refers to messages sent by Peter Strzok.

"Re above re email, it might be more important for (redacted) to know that (redacted) briefed Pence, no?” Page writes.

Strzok responds: "I think that's a good idea. I"ll talk with (redacted) so they build messaging/don't overlap."

The texts continue with Strzok telling Page he consulted "Bill" – a possible reference to his supervisor, Bill Priestap – about who to send to handle the briefing.

Strzok: "Talking with Bill. Do we want (redacted) to go with (redacted) instead of (redacted) for a variety of [reasons]?"

Page: "Hmm. Not sure. Would it be unusual to have show up again? Maybe another agent from the team?”

Strzok: "Or, he's ‘the CI [counter-intelligence] guy.’ Same.might make sense. He can assess if [there] are any new Qs, or different demeanor. If (redacted's) husband is there, he can see if there are people we can develop for potential relationships."

Lawyers for Strzok and Page did not immediately respond to requests for comment.

“This is yet more evidence that the FBI’s Trump-Russia investigation was filled with irregularities," Rep. Devin Nunes, R-Calif., said. "The more we discover about the true origins of the investigation, the more abnormal it appears in every conceivable way.”

In their letter, Grassley and Johnson pressed Barr on the DOJ's review of "FBI surveillance of the Trump campaign," and seeking more information on the transition counter-intelligence briefings as well as media leaks.

"Were these efforts done to gain better communication between the respective parties, or were the briefings used as intelligence gathering operations?" Grassley, R-Iowa, and Johnson, R-Wis., wrote. "Further, did any such surveillance activities continue beyond the inauguration, and in the event they did, were those activities subject to proper predication?"

FOX NEWS EXCLUSIVE: INTERNAL FBI TEXT MESSAGES REVEAL DOJ CONCERNS OVER 'BIAS' IN KEY WARRANT TO SURVEIL TRUMP AIDE

Barr was criticized by Democrats for testifying earlier this month that “spying did occur” against the Trump campaign – an apparent reference to a well-documented surveillance warrant against Trump adviser Carter Page, among other incidents.

Barr stressed that the question for him, as the DOJ reviews the conduct of the original investigation, is whether that "surveillance” was justified and based on solid intelligence.

“Congress is usually very concerned with intelligence agencies and law enforcement agencies staying in their proper lane,” he noted.

The November 2016 text messages may speak to another episode.

A former FBI intelligence officer, who retired after nearly two decades of experience, said the texts conflict with strict rules laid out by Robert Mueller when he was FBI director, known as the FBI's Domestic Investigations Operations Guide (DIOG).

"Based on the formal training all FBI Employees were required to undergo and be tested on with regard to DIOG Sensitive Investigative Matters, these texts indicate both FBI employees were executing investigative strategies on a sensitive investigative matter without any regard for the Mueller/Holder endorsed DOJ DIOG," Timothy Gill Sr. told Fox News.

Regarding the references to new “Qs" and assessing "demeanor," Gill said: "This reference may indicate an ‘outside the box [question]’ that may not fall within the uniform line of briefing questions in an effort to see how the recipient of the question may change their tone or catch them off guard."

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As for using someone’s "husband" to develop “potential relationships," Gill said it was difficult to comment, not knowing who the husband is and whether the spouse was connected to the FBI and DOJ.