FILE - President Donald Trump speaks during a rally at Southern Illinois Airport in Murphysboro, Ill.
FILE - President Donald Trump speaks during a rally at Southern Illinois Airport in Murphysboro, Ill.

U.S. President Donald Trump is stoking new fears over undocumented immigrants just days before next week's national congressional elections and could tighten rules Thursday for migrants seeking asylum in the U.S.

The U.S. leader is speaking about immigration at the White House, his latest attempt to make it the central issue for Republicans in the Tuesday voting. He is then heading to a campaign rally in the midwestern state of Missouri.

In a controversial new campaign ad he posted Wednesday on Twitter, Trump contended without evidence that Democrats allowed a twice-deported Mexican immigrant to stay in the country before he killed two deputy sheriffs in California in 2014.

The ad shows Luis Bracamontes laughing at a court hearing before he was handed a death sentence and profanely vowing, "I'm gonna kill more cops soon."

"Illegal immigrant, Luis Bracamontes, killed our people," the 53-second ad said. "Democrats let him into our country ... Democrats let him stay."

More footage shows unidentified thousands of people storming a barrier at an undisclosed location, with the video asking, "Who else would Democrats let in?"

Trump said atop the ad, "It is outrageous what the Democrats are doing to our Country."

Birthright citizenship

At a campaign rally in Florida late Wednesday, Trump claimed  Democrats want to leave in place a U.S. Constitution provision granting automatic citizenship to everyone born in the U.S., including babies of undocumented migrants who have "been on our soil for only a matter of seconds."

Trump this week said he could change the provision by signing an executive order, but most legal scholars said any changes in the Constitution would have to follow the normal path, a two-thirds vote of Congress or a constitutional convention convened by two-thirds of the country's 50 states.

Trump Birthright Citizenship
Trump, Birthright Citizenship and the US Constitution
Ferocious legal and political battles await any attempt by U.S. President Donald Trump to end birthright citizenship for the children of undocumented immigrants, according to a wide range of scholars, many of whom saw no viable means for Trump to achieve his stated goal."There's no way President Trump can end birthright citizenship by an executive order," Georgetown University law professor Nan Hunter said.

"Hundreds of thousands of illegal immigrant children are made automatic citizens every year because of this crazy policy," Trump said at the rally, "and they are all made instantly eligible for every privilege and benefit of American citizenship at a cost of billions of dollars a year. That's what it costs, billions!"

Trump this week has dispatched more than 5,000 troops to the southern U.S. border with Mexico to block a caravan of several thousand migrants, many of them women and children, from entering the U.S.

Migrants walk along the road after Mexico's federa
Migrants walk along the road after Mexico's federal police briefly blocked the highway in an attempt to stop a thousands-strong caravan of Central American migrants from advancing, outside the town of Arriaga, Mexico, Oct. 27, 2018.

Migrant caravan

The migrants are still more than 1,000 kilometers from the U.S. but Trump has called them "invaders" and says he might send as many as 15,000 troops to counter what he views as a threat to the U.S.

Former Homeland Security chief Tom Ridge, a Republican, rebuffed Trump's claimed Thursday. He told VOA the "use of the word invasion" is "so disproportionate to the potential threat." He said the call for more troops at the border is "unnecessary rhetoric."

"Opiods are a bigger threat," Ridge said. "The terrorists that send pipe bombs to political figures and journalists is a serious threat. The gunman who assassinates people on the Sabbath."

FILE - former Secretary of Homeland Security Tom
FILE - former Secretary of Homeland Security Tom Ridge speaks to a crowd of hundreds protesting in front of the White House in Washington.

Sharp criticism

The Bracamontes ad has drawn a quick rebuke from Trump critics, some of whom called it racist and compared it to a political ad in 1988 supporting then Vice President George H.W. Bush, a Republican, in his successful run three decades ago for the presidency. That ad depicted a mug shot of an African-American felon named Willie Horton, a convicted murderer, who was let out under a weekend furlough program supported by his Democratic opponent, Massachusetts Gov. Michael Dukakis.

While on furlough, Horton raped a white woman and stabbed her white fiance, with the ad stoking white fears of blacks committing crimes against them.

Former U.S. Labor Secretary Robert Reich, who served under Democratic President Bill Clinton and in an earlier Republican administration, said "this may be the most desperate and vile ad since Willie Horton."

A Trump critic, Republican Sen. Jeff Flake of Arizona, tweeted about the Bracamontes ad, saying "this is just a new low in campaigning. It's sickening."

FILE - Luis Bracamontes smirks as the verdict was
FILE - Luis Bracamontes smirks as the verdict was read in the killing of two law enforcement officers, in Sacramento Superior Court, Feb. 9, 2018, in Sacramento, Calif.

The facts behind the Bracamontes case are more complicated than the ad says. He was deported twice after being convicted of drug charges, once in 1997 while Clinton was president, and after again entering the U.S. illegally, in 2001 while Republican President George W. Bush was in office.

Bracamontes, after returning yet again to the U.S., somehow evaded U.S. authorities in the ensuing years, not that any court, government agency or political party allowed him to stay.

From 2003 to 2009, while living at least some of that time in the western state of Utah and working as a house painter and landscaper, he was charged with a string of misdemeanor traffic offenses. Such offenses usually do not trigger fingerprint checks against immigration records, which would have signaled to authorities that he was in the U.S. illegally after twice being deported.

Authorities say he shot the sheriff's deputies near Sacramento, the California state capital, when they checked on his car because they felt something was suspicious.

During his court appearance earlier this year, the Trump political ad shows Bracamontes saying, "The only thing that I [expletive] regret is that I [expletive] killed two ... I wish I killed more of those [expletive]."
National Security Correspondent Jeff Seldin contributed to this story.