Senate Majority Leader Harry ReidHarry ReidConservative Senate candidate calls on GOP to end filibuster Ex-Reid aide: McConnell's 'original sin' was casting ObamaCare as 'partisan, socialist takeover' GOP faces growing demographic nightmare in West MORE (D-Nev.) and Sen. John McCainJohn McCainSenate heading for late night ahead of ObamaCare repeal showdown Two GOP senators back ObamaCare repeal after Ryan call McCain says Ryan's assurance on a healthcare bill is insufficient MORE (R-Ariz.) are calling on President Obama to pardon famed boxer Jack Johnson posthumously. 

The cause has long been a pet project for the senators. While rare, they said posthumous pardons are not unprecedented. 

“We strongly believe that, given the racially-motivated circumstances surrounding Jack Johnson’s case, this conviction should be expunged from his record. Jack Johnson was a tremendous athlete, and his legacy continues to be marred by this miscarriage of justice,” the two wrote in the letter Wednesday. “A posthumous pardon is long overdue, and would be an important step in repairing the legacy of this great boxer and a rare opportunity for our government to right an historical wrong.”

Johnson, the first black heavyweight-boxing champion, was convicted in 1913 under the Mann Act for transporting a white woman across state lines.  The law, intended to stop human trafficking and prostitution, was sometimes used with racial motivation. 

The Senate passed a resolution by unanimous consent last year supporting the pardon on the 100th anniversary of Johnson’s conviction. Last year, Reid, a former boxer himself, also teamed up with Mike Tyson to start an online petition calling for the pardon. 

Both houses of Congress have approved resolutions supporting a pardon, and McCain and Rep. Peter King (R-N.Y.) have introduced resolutions to that effect going back a decade. 

The Obama administration has previously written that it does not process posthumous pardons as a matter of policy. 

According to the Justice Department, Obama has issued only 52 pardons in his more than five years in office.