Donald Trump has claimed Democrats are responsible for allowing an illegal immigrant who killed two police officers into the country, in a new racially charged campaign video.
The video shows Luis Bracamontes, a twice-deported immigrant from Mexico, laughing and threatening to kill more police officers during his trial.
It blames Democrats for "letting in" Bracamontes followed by footage of a Central American migrant ‘caravan’ moving towards the US, warning "who else would Democrats let in?"
Mr Trump has brought immigration to the forefront of the Republican Party’s midterm elections campaign and has been accused by critics of stirring up division through his rhetoric.
The latest video drew criticism from leading Democrats who accused him of "dog whistle" politics.
It has drawn comparisons with the infamous "Willie Horton" advert used against Democratic presidential candidate Michael Dukakis in 1988 and condemned as racist.
Horton, who was black, raped a woman while out of prison on temporary leave as part of a weekend furlough programme. As Massachusetts governor, Mr Dukakis had supported the furlough programme.
Mr Dukakis went on to lose to Republican George HW Bush. Mr Bush distanced himself from the advert.
In a tweet on Wednesday, Mr Trump highlighted the case of Bracamontes, who was sentenced to death earlier this year for the 2014 killings of two officers in Sacramento.
The 53-second spot includes expletives uttered by Bracamontes during his trial as he professed regret at not killing more officials.
"Illegal immigrant, Luis Bracamontes, killed our people!," the video states, adding, "Democrats let him into our country…Democrats let him stay."
Tom Perez, the Democratic National Committee Chairman, called the video "divisive Donald at his worst".
"This is fear mongering. … They have to fear monger and his dog whistle of all dog whistles is immigration," Mr Perez told CNN. "This has been Donald Trump’s playbook for so long."
Republican senator Jeff Flake called the advert "sickening", saying "Republicans everywhere should denounce it".
Jamie Weinstein, the host of a podcast at the conservative National Review Online, tweeted: “This is, without question, a racist ad”.
Mr Trump has repeatedly claimed that a migrant caravan currently heading through Mexico towards the US border contains criminals and "unknown Middle Easterners", without providing any evidence.
On Wednesday he suggested that up to 15,000 troops could ultimately be sent to the US-Mexico border to meet the caravan – more than currently deployed in Afghanistan.
Mr Trump’s rhetoric and his self-identification as a "nationalist" have fuelled debate in light of last Saturday’s massacre in a Pittsburgh synagogue, in which 11 Jews were shot dead by an anti-Semite.
Critics of the president claim Mr Trump’s rhetoric has led to a surge in right-wing extremism and may have helped provoke the synagogue bloodshed.
Mr Trump on Wednesday denied he was anti-immigrant, saying that all successful Republicans are accused of being racist.
“You know the word racist is used about every Republican that’s winning," he said during an interview with CBN News on Wednesday evening.
"Any time a Republican is leading they take out the r-word, the racist word. I’m not anti-immigrant at all."
The Trump administration has rejected the notion that he has encouraged white nationalists and neo-Nazis who have embraced him, insisting he is trying to unify Americans, even as he continues to disparage the media as an "enemy of the people."
During an interview with ABC News, Mr Trump also said he tries to "tell the truth" in office.
“I do try and I always want to tell the truth. When I can, I tell the truth.
"I mean sometimes it turns out to be where something happens it’s different or there’s a change, but I always like to be truthful.”