The chairmen of the House Judiciary and Oversight committees on Tuesday announced a joint investigation into how the FBI handled last year's probe into Hillary Clinton's use of a private email server as secretary of State.

"Decisions made by the Department of Justice in 2016 have led to a host of outstanding questions that must be answered," House Judiciary Committee Chairman Bob Goodlatte (R-Va.) and House Oversight and Government Reform Committee Chairman Trey Gowdy (R-S.C.) said in a joint statement.

The two Republican leaders said they have questions about the FBI's decision to openly declare the bureau's investigation into Clinton's handling of classified information, while quietly investigating Trump campaign associates.

They said they also want to know why the FBI decided to formally notify Congress of the Clinton probe on two separate occasions; why the FBI - rather than the Justice Department - recommended that Clinton not be charged after the investigation concluded; and the reasoning behind their timeline for announcing such decisions.

"The Committees will review these decisions and others to better understand the reasoning behind how certain conclusions were drawn. Congress has a constitutional duty to preserve the integrity of our justice system by ensuring transparency and accountability of actions taken," their statement continued.

Former FBI director James Comey apparently began drafting his statement that the FBI would not recommend charges months before his July 2016 announcement.

Senate Judiciary Committee Chairman Chuck Grassley (R-Iowa) and Sen. Lindsey Graham (R-S.C.) first announced in late August that Comey had drafted a statement on Clinton months before making a public statement, saying the decision was drawn up "before the FBI had interviewed key witnesses."

The revelation sparked a flurry of questions about why Comey waited months after beginning to draft a statement to announce the end of the investigation in the midst of a heated presidential race.

President Trump fired Comey earlier this year, citing his handling of the Clinton probe. Special counsel Robert Mueller, however, is investigating whether Trump fired Comey to obstruct justice in the Russia probes. Comey was leading the inquiry at the time.

The top Democrats on these panels, Oversight's Rep. Elijah Cummings (D-Md.) and Judiciary's Rep. John Conyers (D-Mich.), slammed the decision as an attempt to distract the public eye from the Russia meddling investigation that they said is picking up speed.

"This new investigation is a massive diversion to distract from the lack of Republican oversight of the Trump Administration and the national security threat that Russia poses," the Democratic leaders said in a joint statement, pointing to "ten months of abdication of responsibility" to look into the abuses taking place at the White House.

"The Russian government continues to represent a clear and present threat to the United States and our democratic system, and we are the targets of near-constant cyberattacks by foreign adversaries. Yet House Republicans have taken no concrete steps to secure our next election. Apparently, House Republicans are more concerned about Jim Comey than Vladimir Putin," they said.

Comey has come under scrutiny for the decisions he made regarding the email investigation.

He disclosed during his June testimony before the Senate Intelligence Committee that then-Attorney General Loretta Lynch had urged him to describe the Clinton email probe as a "matter" rather than an investigation.

The ousted FBI chief said her request gave him a "queasy feeling" because it matched "how the [Clinton] campaign was talking about how the FBI was doing its work."