With the Democrats wresting control of the Senate, the US upper house's President pro tempore, who presides over the proceedings in the absence of the Vice President, has a unique qualification.

Patrick Leahy of Vermont, the longest continuously serving Democrat Senator currently, has not only been a lifetime fan of Batman, but has also appeared in five films of the caped crusader, including cameos in the "Dark Knight" trilogy.

The fact was pointed out by comic book fans on social media.

Beginning with an uncredited cameo in "Batman Forever", he voiced a territorial governor in "Batman: The Animated Series" episode "Showdown" (1995), appeared as himself in the film "Batman & Robin" (1997), and appeared twice in the "Dark Knight" Trilogy -- "The Dark Knight" (2008) and "The Dark Knight Rises" as a Wayne Enterprises board member.

He also played Senator Purrington in "Batman v Superman: Dawn of Justice" (2016).

Leahy, 80, has also written forwards to Batman comic books including the "The Dark Knight Archives, Volume 1" (a 1992 collection of the first four Batman comic books), the preface essay for "Batman: Death of Innocents" (a 1996 graphic novel which portrays the horrors of landmines), as well as the introduction to "Green Arrow: The Archer's Quest".

He has also donated all his earnings to the Kellogg-Hubbard library in Vermont where he read the comics as a child.

Leahy, who was first elected to the Senate in 1974 after then President Richard Nixon's resignation over the Watergate scandal, had also earlier served as the President pro tempore, a post which is third in line to the succession to the US Presidency (after the Vice President and the Speaker of the House of Representatives).