Comey said lawmakers had again asked about former Secretary of State Hillary Clinton's emails and a dossier that Republicans claim was used to justify a warrant to conduct secret surveillance of a Trump presidential campaign aide.
Comey also told the House Judiciary Committee that, contrary to Trump's claims, he was "not friends in any social sense" with special counsel Robert Mueller, who is now leading the Russia investigation.
"In 2016, my team faced an extraordinary situation — something I thought of as a 500-year flood — offering no good choices and presenting some of the hardest decisions I ever had to make," Comey wrote.
In a February 2017 conversation, Trump told Comey how Putin told him, "we have some of the most beautiful hookers in the world'' even as the president adamantly distanced himself from a salacious allegation concerning himself and prostitutes in Moscow.
The former FBI director went on to say that a person "who talks about and treats women like they're pieces of meat, who lies, constantly, about matters big and small, and insists that the American people believe it -- that person is not fit to be president."