- The giant balloon named "Trump Baby" was unveiled near the Houses of Parliament, close to where protesters marched to show their discontent against the president and his policies.
- A rally held by the Stop Trump Coalition and other campaign groups started an hour later, with thousands planning to march from London's Trafalgar Square to Downing Street.
- London's Metropolitan Police has put a blockade in place, but protesters will be allowed a clear view of the access to Downing Street.
A 20-foot-tall blimp depicting President Donald Trump in a diaper was raised Tuesday morning in London, with thousands protesting against the U.S. president's state visit to the U.K.
The giant balloon named "Trump Baby" was unveiled at 10:30 a.m. London time near the U.K.'s Houses of Parliament, close to where protesters marched to show their discontent against the president and his policies. Organizers said winds in the U.K. capital had delayed a full flight for the balloon, but by 11:15 a.m. it had been raised 30 feet above the ground.
A rally held by the Stop Trump Coalition and other campaign groups started at 11 a.m. London time, and thousands walked from Trafalgar Square to Downing Street as the president's schedule unfolded. London's Metropolitan Police put up a blockade, but protesters were allowed a clear view of the access to the prime minister's residence at 10 Downing St.
"Now Trump is coming back for a state visit and we have to get out there again in a diverse Carnival of Resistance that shows we reject Trump's divisive politics and policies of bigotry, hate and greed," the Stop Trump Coalition said on its website ahead of the demonstration.
The group's Facebook event, called "Together Against Trump – stop the state visit," had more than 8,500 potential attendees and 34,000 people interested in attending. It is one of a string of protests against the president's visit that are being organized in different cities across the country.
In 2018, a mass protest in London against Trump's visit attracted tens of thousands of people and the security costs amounted to an estimated bill of more than £12 million ($15.8 million). Tuesday's numbers were far lower than at last year's demonstration.
Jeremy Corbyn, leader of the U.K.'s Labour Party, will speak at Tuesday's protest, a spokesperson for the party told British media. Corbyn said Monday on Twitter that the demonstration was "an opportunity to stand in solidarity with those he's attacked in America, around the world and in our own country."
In a tweet on Monday evening, Trump said his visit was "going really well" and that there had been "tremendous crowds of well wishers."
"Haven't seen any protests yet, but I'm sure the Fake News will be working hard to find them," he added.
At a joint press conference with U.K. Prime Minister Theresa May on Tuesday afternoon, Trump was quizzed on how he felt about the demonstrations against him. The U.S. leader replied that he had been told about the dissent, but he had seen almost no evidence of it.
"I didn't see the protesters until a short while ago and it was a very small group of people, put in for political reasons, so it was fake news," Trump said.
Trump insisted that he instead witnessed "thousands of people on the streets cheering" as his cavalcade made its way through London on Monday.
Trump and his family will be in the U.K. until Wednesday, when he is due to fly to France to attend a D-Day ceremony in France with French President Emmanuel Macron.
Asked about protests ahead of his 2018 U.K. visit, the president said: "I think it's fine. I think they like me a lot in the U.K., I think they agree with me on immigration." However, he later told British newspaper The Sun that the protests made him feel "unwelcome."
Before landing in London on Monday, Trump tweeted a strongly worded criticism of the city's mayor, Sadiq Khan, after Khan likened the president to "the fascists of the 20th century." Trump accused Khan of being incompetent and "foolishly 'nasty' to the visiting president of the United States," before dubbing him a "stone cold loser."
The angry-orange baby balloon that flew on Tuesday has been a point of tension between the president and the mayor. Khan did not authorize its use in 2018 at first, but then changed his mind after more than 10,000 people signed a petition calling for him to do so. Khan explained in an interview that there's no reason to stop the balloon given that it is a safe and peaceful way of protesting.
—CNBC's Hollie Wong contributed to this article.