WASHINGTON – President Donald Trump shared an ad from his Twitter feed that said Democrats are responsible for a Mexican citizen who killed two California deputies, and Trump's critics have called the spot racist and divisive.

"Illegal immigrant, Luis Bracamontes, killed our people!" reads the opening text in a campaign ad tweeted by Trump on Wednesday.

"Democrats let him stay," the next line reads.

The man featured in the video is Luis Bracamontes, a Mexican citizen who had repeatedly entered the U.S. illegally and was sentenced to death for the murder of two Sacramento County sheriff's deputies.

The inflammatory ad is part of Trump's ongoing push to make immigration a key issue ahead of the midterm elections next week.

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"It is outrageous what the Democrats are doing to our Country. Vote Republican now!" the president tweeted alongside the ad.

The 53-second spot, which CNN reports was produced by the Trump campaign, is being derided by many as the most racially charged campaign commercial since the infamous 1988 "Willie Horton ad."

"This is distracting, divisive Donald at his worst," Democratic National Committee Chairman Tom Perez told CNN. Perez characterized the commercial as "dog whistle politics" based on "fear-mongering" and a desperate move ahead of the midterm election. Pollsters have predicted the Democrats will gain a majority in the House of Representatives.

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During his trial, Bracamontes was removed from the courtroom for threatening outbursts. At the reading of his verdict in February, Bracamontes smiled and vowed to "to kill more cops soon." The commercial centers on Bracamontes' antics, while the text tells the viewer that "Democrats let him stay."

The video, which had 3.9 million views as of 6 p.m. EDT Thursday, then cuts to scenes of apparent migrants crashing through unspecified gates.

"Who else would Democrats let in?" the ad asks rhetorically in conclusion, before closing with a message that "President Donald J. Trump and Republicans are making America safe again."

Immigration has long been a top issue for Trump since he entered politics, but in recent weeks, he has stepped up the tempo in his warning cries about an "invasion" across the U.S.-Mexico border.

He has used his platform to help keep up step-by-step media coverage of a caravan of Central American migrants traveling north through Mexico. On Wednesday, the president threatened to deploy 15,000 U.S. troops to the border in response to the approaching caravan, which is made up of people fleeing corruption, violence and poverty in their home countries.

Also this week, Trump began to argue he can end birthright citizenship, which is rooted in the 14th Amendment, with an executive order.

It is not the first 2018 midterm campaign commercial paid for by Trump's 2020 presidential campaign. Another ad that says a Democratic victory would endanger the country's economic gains, but never mentions Trump, began airing Monday as part of a $6 million ad buy.

"You have to make people feel things. I think that's what commercials are, from a commercial for a car, a phone or anything that might be," Trump campaign manager Brad Parscale told CNN about the "We Can't Go Back" ad.

In response to the new ad featuring Bracamontes, Arizona Republican Sen. Jeff Flake, a Trump critic, said, "This is just a new low in campaigning. It's sickening," according to CNN's Jake Tapper.

Several critics compared the ad to a conservative PAC commercial for former President George H.W. Bush's successful 1988 campaign to succeed President Ronald Reagan. The ad centered on William Horton, a convicted murderer who fled custody after being released as part of a weekend furlough program supported by Bush's Democratic opponent, former Massachusetts Gov. Michael Dukakis. Horton committed a violent rape while out of prison.

The ad is often referred to as a negative example of capitalizing on racial anxieties for political gain. Princeton University history professor Kevin Kruse argued that Trump's ad is actually "so much worse" because, "Unlike the Willie Horton ad – which was outsourced to third parties" this "new ad is coming directly from the personal Twitter account of the president himself."

"And it isn't just that the president of the United States is personally pushing white nationalist politics in its ugliest and crudest form, it's that he's doing it proudly and with purpose," Kruse tweeted.