Mr Trump called the Maryland city a "disgusting, rat and rodent infested mess" where "no human being would want to live”.
It was not clear whether he would get a chance to see the latest inflatable to mock him. The “Trump Rat” depicts him as a giant rodent with slicked back yellow hair, a red tie and holding a mobile phone.
It was being driven around on the back of a black truck along with a couple of small “baby blimps” similar to the one first seen in London during the president’s visit to the UK last year.
To reinforce the message, the inflatable rat was being displayed on a street adorned with a sign reading President Barack Obama Ave.
One of the protesters behind the “Trump rat”, Claude Taylor, told the Baltimore Sun: “The rat’s been in Newport Beach, California, on a boat, it’s been on the Potomac on a boat. It’s been most notably docked off Mar-a-Lago.”
Other protesters joined the rodent theme, with one holding a model of the president as a rat, while another wore a Trump mask and striped prison uniform.
The US leader’s broadside against Baltimore was widely seen as revenge for criticism by Elijah Cummings, the Democratic congressman who heads the House oversight panel, which is overseeing several investigations into the administration.
Kevin McCarthy, who heads the Republican minority in the House, said the president had “made a very good case why many major cities have challenges”.
He added that Mr Trump’s trip there “symbolises that, yes, he cares about Baltimore” and wants to give people living in poverty “a better opportunity”.
Baltimore has well documented problems with drug crime - famously dramatised in the award-winning television series The Wire.
Last year the city saw more than 300 violent deaths for the fourth year running.
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