Biden, who often speaks with pride of his Irish roots, hosted Irish Prime Minister Leo Varadkar at a St. Patrick's Day event on Friday.
While speaking at the event, Biden also introduced his distant relative and ex-Ireland fullback Rob Kearney, saying, "we've even got a few of my distant Irish cousins here today...
"Rob stand up. I want to see you after this, pal. You know, Rob, I expect, we know, and this is no offence to anyone in the room, who we are rooting for in the Grand Slam match between Ireland and England."
In 2016, after Ireland beat New Zealand for the first time, Biden tweeted: "Congrats to cousin @KearneyRob on behalf of the Bidens. @IrishRugby's 1st win over New Zealand in 111 years."
Top-ranked Ireland lead the Six Nations table by four points from second-placed France and will be looking to clinch a fourth clean sweep when they take on England in Dublin on Saturday.
