Story highlights House Republicans are investigating the Justice Department's probe into Clinton's email server

James Comey's June 2017 public testimony contained numerous bombshell revelations

(CNN) House Republicans are preparing to ask former FBI Director James Comey to testify as part of the Republican-led probe into the FBI and Justice Department handling of the Hillary Clinton email investigation.

Comey's testimony, if he appeared, would raise the stakes of the joint Judiciary and Oversight Committee investigation into the decision not to charge the 2016 Democratic presidential nominee over classified emails on her private server — and the rare step for Comey to publicly announce Clinton would not be charged — as the probe has become a proxy battle on Capitol Hill between Democrats and Republicans over special counsel Robert Mueller's investigation.

Several Republicans told CNN that Comey is a key witness for the investigation, although it's not clear how soon he would be asked to testify.

"I think that would be essential," said Rep. Matt Gaetz, a Florida Republican who has led a group of conservatives calling for Mueller to be fired. "We're going to have to find out from James Comey why the normal procedures were ignored in this case."

"I hope there's a chance at some point that we get to talk to Mr. Comey, either a deposition or under oath in a committee hearing," said Ohio Republican Rep. Jim Jordan, who last week called for Attorney General Jeff Sessions to resign over mismanagement of the Russia probe and leaks from the FBI.

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