And then, of course, he commented at length.
He said: "I don't think another vote would be possible because it would be very unfair to the people that won".
Speaking about his earlier private meeting with Mr Varadkar, the United States president said: "We discussed a lot of things, in particular we talked about Brexit, something that turned out to be a little more complex than they thought it be".
Asked if Brexit is likely to be delayed, Mr Trump said: "I think they are probably going to have to do something because right now they are in the midst of a very short period of time - the end of the month - and they are not going to be able to do that". "I regret that Brexit's happening". Varadkar even spoke about his sexuality at the Naval Observatory.
Leo Varadkar is in America as part of the annual St Patrick's Day celebrations in Washington DC.
He said he would like to see the "whole situation with Brexit work out", adding "we are talking with them about trade and we can do a very big trade deal with the UK".
For most USA presidents, the kitschy tribute to Ireland is good politics.
There is perhaps nowhere as fitting for President Trump to visit than a home away from home, The White House department store.
Thursday's events carried on despite awkward timing.
While Varadkar prepared to have breakfast with Pence and a who's who of Irish-Americans, including the president of Notre Dame, Trump tweeted an open invitation to Britain to free itself of the European Union and its trade rules.
But he now he says: "The potential is unlimited!"
"We shouldn't have a hard border or anything to obstruct the peace process".
The Irish PM said the most pressing issue facing his country was how to settle questions about the future of the border between Ireland, an European Union member, and Northern Ireland, which won't be.
Mr Trump spoke during the lunch
While speaking to the press, Trump mentioned his property in Doonbeg, Clare and said that he plans on visiting Ireland.
"I predicted it was going to happen, and I was right".
Mr Trump said: "I am coming at some point during the year".
The bowl presented to Mr Trump, in the company of his wife, Melania, was made at Kilkenny Crystal in Callan, the home town of Irish-American architect James Hoban.
MPs are set to vote on Thursday evening on whether to request a delay until at least June.
"I think it could've been negotiated in a different manner, frankly".
"It's just a great place", he added.
After he met Pence at his home a year ago, Varadkar told Irish reporters that the two discussed LGBT issues and that the vice-president told the Irish leader that his partner would be welcome at his home.
"The Irish government has played a very adversarial role", Gardiner said.
Pence glossed over the Brexit disagreement as he welcomed Varadkar for the breakfast, and grew nostalgic as he recounted his grandfather's emigration from Ireland and his own affection for the country.
Pence called Varadkar's remarks at Thursday's breakfast "inspiring words".
During the annual event, the Taoiseach presented the U.S. president with a bowl of shamrock to mark his St Patrick's visit to Washington DC.
Of his Irish grandfather, VP Pence said: "He was proud of being American but I can still hear that Irish brogue".
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