The Labour leader addressed crowds of protesters on Tuesday as Mr Trump met the Prime Minister.
The signs carried messages such as, "Dump Trump" and "Trump not welcome", while a blimp depicting Trump as a giant baby with tiny hands floated outside Parliament as the president passed. "She's probably a better negotiator than I am".
He added: "You know what?" "Obviously, it will be whoever succeeds me as prime minister to take this issue forward".
"She was nasty to me", Trump said. May and her aides chuckled at that.
Trump and Merkel discussed Libya and conditions in West Africa during their roughly 10-minute meeting, said White House press secretary Sarah Sanders.
It is traditional for USA and other world leaders to not weigh in on another's domestic politics.
Louisiana Passes Fetal Heartbeat Abortion Bill, Dem Governor Says He’ll Sign
In his statement , Edwards seemed determined to prove his Democrat credentials, essentially apologizing for his pro-life stance. Louisiana's latest abortion ban won support from many Democrats and was sponsored by Democratic Sen.
The balloon was the focal point of last year's rallies against the president's working visit to Britain, and was back by "popular demand", according to organiser Leo Murray, a full-time climate activist. "Not on my watch", Hancock, who is a contender to replace May as prime minister, said on Twitter.
Trump has talked up a trade pact with a post-Brexit Britain from the start of his presidency, often putting May in a tricky spot, since Britain can not fully negotiate a deal while still a part of omnibus European Union trade arrangements.
Donald Trump Jr. and Eric Trump, who are handling the president's business affairs while he's in office, as well as Tiffany Trump, showed up at the state banquet and for other parts of the president's visit, with no explanation for their presence from the White House.
Supporters of Mr Trump also took to the streets.
The White House said clearly earlier this year that any trade deal should include "reimbursement regimes [that] are transparent, provide procedural fairness, are non-discriminatory, and provide full market access for U.S. products". Others in the United Kingdom are pressing for a second referendum that could keep Britain in the EU. Still licking their wounds from Brexit's second big win, the British left is lashing out at the biggest symbol they can find for their troubles: the visiting president of the United States.
A Labour spokesperson had said that Corbyn proposed to meet with Trump, The Independent reported.
Trump will attend a luncheon with May at Downing Street.
Protesters' banners at Trafalgar Square displayed similar sentiments.
Facts First: Trump did predict Brexit, which few people saw coming. "There was great love", he said.
The onslaught of disjointed news and commentary threatened to distract from Trump's goal for the visit - to pay tribute to the veterans of the battle that shifted the course of World War II 75 years ago.