Reid, D-Nev., and Sen. Mo Cowan, D-Mass., announced Tuesday they are joining Sen. John McCain, R-Ariz., and Rep. Peter King, R-N.Y., in working to persuade President Barack Obama to get Johnson, who died in 1946, a posthumous pardon for what is regarded as a racially motivated conviction, the Las Vegas Sun reported Wednesday.
Johnson won the heavyweight title and kept it until 1915, but was convicted in 1913 for violating the Mann Act, designed to prevent prostitution and "immorality" but often exploited to intimidate interracial couples.
Many have since argued Johnson, a charismatic black superstar, was persecuted for his involvement with white women, the newspaper noted.
"Johnson's memory was unjustly tarnished by a racially motivated criminal conviction, and it is now time to recast his legacy," Reid said in a statement.
The House and Senate previously passed resolutions to posthumously pardon Johnson, but no president has granted the pardon.