George Mitchell and Gerry Adams are among the others set to attend the forum in Washington DC
The Taoiseach will give the keynote speech at an event marking the 20th anniversary of the Good Friday Agreement in Washington DC today.
The event will take place at the Library of Congress on Capitol Hill, as Leo Varadkar continues his St Patrick's week visit to the States.
His trip will culminate with a meeting with Donald Trump in the White House on Thursday.
The Taoiseach says he has asked the pro-Trump governors of Texas and Oklahoma how to approach the US President.
He explained: "I have asked, because most of them have met him on occasion.
"What they've all said to me is that it is what you expect - the person who you see on TV is the same person you'll meet in the office."
Leo Varadkar has been getting advice from a couple of US State Governors about how to deal with Donald Trump on Thursday pic.twitter.com/vbdCZYJ3jB— Sean Defoe (@SeanDefoe) March 12, 2018
The Taoiseach stressed that he isn't apprehensive about his White House visit, and is in fact looking forward to meeting both President Trump and Vice President Mike Pence.
Mr Varadkar observed: "I think there is a risk of widening differences and widening gaps between Europe and America... around issues such as tax, trade, different approaches to climate change, security.
"I actually think that's where Ireland can have a very important role - being a bridge between America and Europe, interpreting one to the other. That's a role that will perhaps become more important in the future, particularly as the United Kingdom leaves [the EU]."
Today's forum commemorating the anniversary of the Good Friday Agreement will also feature speakers including former US special envoy to Northern Ireland George Mitchell, former Sinn Féin leader Gerry Adams, and SDLP leader Colum Eastwood.