Theresa May struck Donald Trump's criticism of Brexit's business as he began a two-week effort to sell his deal.
Just two weeks before the House of Commons holds a critical vote on divorce settlement in the EU, the prime minister is struggling to win skeptical deputies.
Her efforts have suffered a major blow when Mr Trump stated that the Brexit agreement "seems to be a big part" for the EU.
The US President also suggested that regulatory terms would hamper the United Kingdom's ability to sign a post-Brexit trade agreement with America.
However, Ms. May defended her Brexit plan, while on Tuesday paid her visit to Wales and Northern Ireland.
The prime minister insisted that the 26-page political declaration on the future EU-UK relationship agreed with the UK withdrawal agreement means "we will be able to negotiate trade negotiations with countries in the rest of the world."
Visiting the Royal Welsh Winter Fair in Builth Wells, Ms. May also claimed that Great Britain and the US are already working "very well" on the terms of a new trade agreement.
She added: "As far as the US is concerned, we have already talked about the type of agreement that we may have in the future.
"We have a well-established and well-functioning working group, met several times and continue to work with the US in this regard."
Ms. May expects to visit all regions of the UK during the campaign to sell her Brexit business before the lawmakers vote on December 11, the premier traveled later to Northern Ireland.
After meeting with business leaders, young farmers and students at Queen Belfast University, Ms. May held talks with Northern Ireland's political parties.
However, the meeting with DUP leader Arlene Foster, whose party supports Mrs. May's government at Westminster, seems to be unsuccessful in removing the opposition to her Brexit agreement.
Following talks, Ms. Foster repeated the Prime Minister's request to renounce the so-called Irish Border Arrestment Arrangement, despite the fact that Ms. May insisted that Brussels would not accept it.
Ms Foster said: "The EU will obviously say that the right can not be changed until it accepts the change.
"There is currently no pressure on them to change their position, as the UK does not even ask."
The DUP leader earlier made Ms. May's visit to Northern Ireland as "a waste of time," saying Sky News: "Would not it be better to spend time trying to get a better deal?
"In trying to get a deal, we can join in instead of wasting time around the country for two weeks."
Chief Maye's chances of doing his job in parliament seem to be thin, estimating that there could be more than 60 votes to win the House of Commons support.
Former Secretary of Defense, formerly loyalist Sir Michael Fallon, added to the Prime Minister's victories when he marked his business "condemned" and said he would not vote for it.
Ex-foreign secretary Boris Johnson continued his attack on the prime minister, squandering his plans to discuss the deal with Labor Leader Jeremy Corbyn.
"There is no point in having a debate with two people who have voted" Remain "and agreements that do not regain control," he said.
However, Ms. May received support when Japanese Prime Minister Shinzo Abe welcomed the fact that he reached an agreement with Brussels in a phone call between the two leaders.
An initial plan to sell a Brexit agreement, which was leaked before a deal with Brussels, suggested that Downing Street hoped to support world leaders such as Mr Abe.
On Wednesday, the government will publish economic analyzes of the various Brexit scenarios.
However, opposition MPs also urged the government to publish full legal advice on the withdrawal agreement in the coming days, and Parliament will support earlier this month that ministers will make this information available.
The government was also attacked after state secretary Sajid Javid was unable to say whether plans for a post-Brexit immigration system would be published before Deputies voted the Brexit agreement.