Biden’s intervention is historically unprecedented. After President Franklin D. Roosevelt signed the National Labor Relations Act into law in 1935, the leaders of the newly organized industrial unions declared that “The president wants you to join a union.” But FDR never actually said that.
In this case, Biden gave no indication of impartiality, all but calling on workers to vote the union in and accusing Amazon of intimidation. Biden is putting the entire prestige of the White House behind the vote. He would not have done this unless he felt that the direct support of his administration was both necessary to ensure a “yes” vote in Bessemer and strategically important.