Mr Trump said: "I'm surprised at how badly it's all gone from the standpoint of a negotiation".
If passed, it will order Theresa May to seek to delay Brexit "for the purposes of legislating for and conducting a public vote in which the people of the United Kingdom may give their consent" for either leaving the European Union on the terms of a deal agreed by Parliament or remaining in the bloc.
But it warns that if her Agreement is rejected for a third time - following overwhelming defeats by 230 votes in January and 149 votes this week - any extension would have to be longer and would involve the United Kingdom taking part in European Parliament elections in May. But "she didn't listen to that and that's fine".
"I understand why they may not find the Prime Minister's deal perfectly in line with their view of the optimum future relationship", he told Sky News. A cross party amendment from Labour's Hilary Benn and Yvette Cooper with Tory Oliver Letwin wanted to cancel Government business next Wednesday was defeated 314 to 312 after Theresa May's deputy David Lidington promised MPs the Government would stage its own indicative votes after next week's European Union summit if the Brexit deal fails again. "I mean she's got to do what she's got to do", he said at the White House as he welcomed Irish Prime Minister Leo Varadkar for an early St. Patrick's Day celebration. "I hate to see everything being ripped apart now".
Trump predicted later Thursday that the situation eventually would work itself out. "I don't think another vote would be possible because it would be very unfair to the people that won", Trump said.
The Republican president was at the Capitol just hours before 12 GOP senators broke ranks and voted to reject his declaration of a national emergency at the U.S. -Mexico border.
The Democratic-run House, led by Speaker Nancy Pelosi of California, voted last month to block the declaration.
Mr Varadkar replied: "We have a different opinion, Mr President".