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President Donald Trump on Wednesday released a racially divisive political ad that blames Democrats for allowing an undocumented immigrant who was convicted of killing police officers to stay in the U.S.

The 53-second video, which was pinned to the top of Trump’s Twitter feed on Thursday, refers to Luis Bracamontes, who was convicted and sentenced to death this year for killing two California police officers in 2014.

Bracamontes is from Mexico and was in the U.S. illegally in 2014 at the time of the murders. He had been deported twice, but returned to the U.S. illegally both times.

It is outrageous what the Democrats are doing to our Country. Vote Republican now! https://t.co/0pWiwCHGbh pic.twitter.com/2crea9HF7G — Donald J. Trump (@realDonaldTrump) October 31, 2018

The ad — which comes amid a renewed push by Trump just days before the midterms to focus on illegal immigration — opens with text stating: “Illegal immigrant, Luis Bracamontes, killed our people!”

“Democrats let him into our country … Democrats let him stay,” the text continues, over video from Bracamontes at his sentencing hearing earlier this year, during which he said, “I don't f------ regret that.”

The ad then shows video of the migrant caravan heading north through Mexico, followed by text that reads, "Who else would Democrats let in?"

Trump provided no evidence for his claim that Democrats are responsible for Bracamontes' presence in the country, and support appears scant. Trump has routinely painted sanctuary cities — jurisdictions in which local authorities do not comply in some way with federal immigration authorities — as hotbeds of crime that allow dangerous criminals to roam the street. Evidence doesn't support his claims that sanctuary cities are more dangerous than other cities, but even so, Sacramento County, which is largely Democratic and where the killings took place, is not a declared sanctuary jurisdiction for undocumented immigrants, according to The Sacramento Bee.

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Bracamontes assumed several different identities while he was in the country illegally, and law enforcement officials said at the time of his arrest they did not have a "full picture of his identity," according to The Associated Press. Bracamontes was first deported in 1997, during the administration of Democratic President Bill Clinton, after being convicted of possession of narcotics for sale. He was then arrested and sent back to Mexico again in 2001 under President George W. Bush, a Republican.

Joe Arpaio, a Republican and the former Arizona sheriff who is an immigration hard-liner and outspoken Trump supporter, told NPR in 2014 that Bracamontes, who also committed crimes in Arizona, may have "slipped through the cracks."

Kevin Johnson, an expert on immigration law and dean of the University of California Davis School of Law, told NPR in 2014 that the case is "a tragic event that's really an exception as opposed to the rule." Johnson added that when Bracamontes was in federal immigration custody, he was deported, which is an example of the system working.

Trump has repeatedly tried to pin blame on Democrats for the state of immigration, claiming they refuse to close so-called loopholes in immigration law and falsely stating that the party was at fault for his administration's police of separating migrant families at the border. Trump even appeared to threaten a government shutdown over immigration "loopholes" in February.

Democrats quickly slammed Trump for the ad, with some comparing it to the "Willie Horton" ads that ran during the 1988 presidential campaign.

This may be the most desperate and vile ad since Willie Horton. Trump and Republicans don't want to talk about the fact that they plan to repeal the ACA, gut Social Security, Medicare, & Medicaid, and cut taxes even further for their donors, so they've resorted to fearmongering. https://t.co/xaXNThEOfb — Robert Reich (@RBReich) October 31, 2018

"This is distracting, divisive Donald at his worst," Democratic National Committee Chairman Tom Perez told CNN, adding that the ad is the "dog whistle of all dog whistles."

Former Secretary of Labor Robert Reich tweeted that it was "the most desperate and vile ad since Willie Horton" and slammed Republicans for having "resorted to fearmongering."

The now-infamous ad, which ran in support of George H.W. Bush during the 1988 campaign, features a mugshot of Horton, who is black, and used his case to attack Democratic presidential candidate Michael Dukakis as soft on crime. When Dukakis was governor of Massachusetts, Horton, who was serving a life sentence for murder, raped a woman during a weekend furlough from prison. The ad played into racial fears and is credited with helping to cost Dukakis the election, but it was also widely condemned.

Some conservatives also criticized the Bracamontes ad.

“This is, without question, a racist ad," tweeted Jamie Weinstein, the host of an eponymous podcast show at the conservative National Review Online.

Sen. Jeff Flake, R-Ariz., called the add "sickening" in a tweet Thursday afternoon.

"This is a sickening ad. Republicans everywhere should denounce it," he wrote.

Trump's re-election campaign released an ad this past January that also featured Bracamontes and, without evidence, claimed that Democrats were "complicit" in the killings of law enforcement officers, according to the AP.

In the last days before next week's midterm elections, Trump has tweeted repeatedly about illegal immigration, putting the hot-button issue front and center.

He's repeatedly railed against the caravan of migrants and refugees heading north through Mexico and, earlier this week, said he would send thousands of U.S. troops to the border and planned to end birthright citizenship with an executive order.