Video report by ITV News Washington correspondent Robert Moore
Donald Trump's latest video advert released ahead of the mid-term elections has been branded as 'racist' and 'fearmongering.'
The video features a Mexican immigrant who returned to the United States after being twice deported to Mexico and killed two Californian policeman in 2014.
Luis Bracamontes, who was given the death penalty for his crimes, was an illegal immigrant at the time of shooting - a fact Mr Trump's ad hones in on.
Meanwhile, speaking at the White House on Thursday, the president claimed the thousands of migrants heading for the southern US border were not "legitimate" asylum seekers, and warned that anyone caught throwing rocks would be treated as though they were using a rifle.
In the video, shared on Twitter by Mr Trump, Mr Bracamontes is shown as having little remorse for his actions with a caption that reads "illegal immigrant, Luis Bracamontes, killed our people!"
As the clip progresses another caption appears stating: "Democrats let him into our country".
The advert also includes footage of thousands of unidentified people rioting along with a Fox News interview featuring a "deported immigrant in caravan" asking to be pardoned for murder.
It is then followed by a caption which reads: "who else would Democrats let in".
Since Mr Trump shared the video on Twitter it has already garnered more than three million views, at the time of writing.
In response to accusations made in the advert, Democratic National Committee Chairman Tom Perez said it was an example of the President "at his worst".
He told CNN: "This is distracting, divisive Donald at his worst, this is fearmongering."
Historians have compared the latest advert to one used by George H.W. Bush to attack his Democratic opponent, Michael Dukakis, in the 1988 presidential elections.
The Willie Horton advert featured an African American felon and was used to show Democrats as being soft on crime.
In a discussion with reporters after the advert appeared online, Mr Trump went on to insist that a caravan of some 1,600 migrants heading for the US to seek asylum were not "legitimate".
The group began in early October with 160 Hondurans, but numbers have swelled as they made their way north.
The government of Mexico has generously offered asylum, jobs, education and medical care for people within the caravan, but many members of the caravan have refused these offers, which demonstrate that these migrants are not legitimate asylum seekers.
He went on to discuss accusations that some members of the migrant group had thrown rocks at the Mexican military, and warned that should the same happen to US troops, they would "fight back".
"We're going to consider it, and I told them, consider it a rifle," he said.
The president had previously stated he would send up to 15,000 troops to the border before the caravan arrives to ensure the United States is "not letting them in".
"These caravans and illegal migrants are drawn to our country by Democrat-backed laws and left wing judicial rules. We are getting rules that are so ridiculous, so bad, they are writing the laws. Can't do that," he said.