Strzok's lawyer is blaming political pressure over the text messages for Strzok's firing last Friday.
The lawyer, Aitan Goelman, criticized the firing in a statement Monday, saying he was sacked because of political pressure and "to punish Special Agent Strzok for political speech protected by the First Amendment". The FBI had been reviewing his employment.
The texts between Strzok and Lisa Page have ignited conservative corners of the internet for months.More news: Trump signs $717bn annual defence policy bill into law
He added that Comey's team was using personal email addresses and sending classified information on them while investigating Hillary Clinton and portraying themselves as heroes. Clinton was cleared in the probe.
The decision to fire Strzok should be "deeply troubling to all Americans", said his attorney Aitan Goelman.
There is no indication that the probe will be dropped.
"It is a total Hoax", Trump said of the Russian Federation investigation.
Monday, the president called for the Mueller investigation to be "properly redone" in light of Mr. Stzok's involvement.
North Carolina Republican Rep. Mark Meadows, one of the leading critics of the FBI investigations, said Strzok was sacked "because of what his own written words plainly showed: he was willing to use his official FBI position to try and stop President Trump from getting elected".