FIRST ON FOX — Senate Republicans plan to launch their own investigation next month that delves into the alleged “conspiracy” behind former President Joe Biden’s cognitive decline. 

Sens. Eric Schmitt, R-Mo., and John Cornyn, R-Tx., announced plans to hold a Senate Judiciary hearing on June 18 to probe into the alleged cover-up of the 82-year-old former president’s mental decline while in office by the media and those closest to him.

The lawmakers are still gathering witnesses for the probe, which would be the first full congressional committee hearing on the subject.

“It’s time to expose how a cadre of Biden aides and family members were the de-facto commander-in-chief, while President Biden was sidelined,” Schmitt said in a statement to Fox News Digital. “I look forward to getting the American people the answers they deserve.”

SCOOP: GOP PUSH FOR NEW HOUSE COMMITTEE TO PROBE BIDEN DECLINE ‘COVER-UP’ GAINS STEAM

Both lawmakers contended that Biden’s decline was hidden for “years.” Cornyn argued that the country depended “on having a president who has the mental capacity to do the job, and it’s clear that President Biden did not, so we must use this hearing to uncover the facts.”

KEY BIDEN STAFFERS ASKED TO TESTIFY ON ALLEGED ROLE IN MENTAL DECLINE ‘COVER-UP’

“For this conspiracy between the mainstream media, Joe Biden’s family, and his inner circle to have hidden the impairment of the President of the United States for years, and lied consistently to the American people about his capacity to make decisions, which are solely vested by the Constitution, is unacceptable,” he said in a statement to Fox News Digital.  

Both Schmitt and Cornyn join a growing chorus of Republicans demanding answers about what really went on behind-the-scenes during Biden’s presidency. 

In the House, lawmakers are pushing to create a select committee that would investigate the Biden administration’s alleged cover-up. 

Rep. Buddy Carter, R-Ga., is leading the charge to create the panel and introduced legislation on Thursday to start the committee that would dive into “the potential concealment of information from the American public,” regarding Biden’s health.  

And House Oversight Committee Chair James Comer, R-Ky., has called on several high-ranking staffers from the Biden White House to participate in transcribed interviews regarding their alleged roles in covering up the former president’s decline. 

Comer called on former director of the Domestic Policy Council Neera Tanden, former assistant to the President and Deputy Chief of Staff Annie Tomasini, former senior adviser to the first lady Anthony Bernal, former deputy director of Oval Office operations Ashley Williams and Biden’s physician, Dr. Kevin O’Connor, to participate. 

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The growing fervor by Republicans to uncover whether Biden’s allies and family hid concerns about his health from the public comes on the heels of the release of “Original Sin” by CNN host Jake Tapper and Axios reporter Alex Thompson. 

Their book claimed that the Biden White House was trying to control the narrative surrounding the former president’s health, and that his allies worked to cover up his decline.