Anticipation that Republican presidential candidate Donald Trump might moderate his position on immigration in a long-awaited "pivot" to the general election was extinguished on August 31 when he laid out his 10-point immigration plan in a fiery speech in Arizona.

Instead of a more compassionate and humane platform, he reverted to his fulminating and nativist rhetoric, vowing to deport two million "criminal aliens" immediately and rejecting any path towards legalisation for the nation's estimated 11 million undocumented immigrants, who would have to return to their home country and wait their turn in the long immigration queue.

It was unclear how aggressively Trump would pursue law-abiding immigrants, though they would be pushed further into the shadows, including those brought to the country as children who have never known another home.

Mexico visit

The speech stood in stark contrast to Trump's hastily arranged visit to Mexico to meet with President Enrique Pena Nieto hours earlier.

The trip was presumably a gambit to appear adept at diplomacy, while appealing to Latinos and moderates put off by his previous disparagement of Mexico and its people and his hard line on immigration.

During the seemingly smooth visit, Trump appeared relatively muted and conciliatory, reading from a prepared text at the joint news conference.

There is not a consensus in the US about how to deal with those who are not legally in the country, and reasonable minds can differ about a sound and humane policy without being xenophobic.

But the cordial visit was quickly overshadowed by an unfolding dispute between the candidate and the Mexican president about whether the pair discussed who would pay for the wall Trump has long promised to build to protect the country's southern border- at Mexico's expense.

Trump insisted the issue of who would bear the costs did not come up, while Pena Nieto said he made clear from the outset that Mexico would not pay for a wall.

If Trump intended to burnish his credentials at statecraft, Pena Nieto's later comments that the candidate's policies pose a "huge threat" to Mexico was an inauspicious start.

The facts on the ground

In the speech, Trump doubled down on his vilification of immigrants, featuring the anguish of families whose loved ones had been murdered by undocumented immigrants.

They are indeed tragic stories, but they are hardly representative. To bolster the point about the criminality of immigrants that has long been part of his nativist grand narrative, Trump cited the misleading statistic that 25,000 immigrants?have been arrested for homicides.

While that claim is technically true, it covered a period from 1955 to 2010. By comparison, more than 11,000 people born in the United States were arrested for homicide in 2010 alone.

And multiple studies have found that immigrants - both those here legally and those without legal status - commit crimes at a lower rate than people born in the US.

Even if the claims of malfeasance were accurate, the appropriate response would be focusing efforts on deporting criminals and security threats - the very policies the Obama administration has aggressively pursued, along with targeting recent border crossers (PDF).

And Trump's insinuation about the deleterious impact of immigrants is contradicted by studies finding that they actually make communities safer, not less so. Unsurprisingly, the speech won praise from white nationalists.

Aside from crime, Trump lamented the "record pace of immigration and its impact on [the nation's] jobs, wages, housing, schools, tax bills and general living conditions".

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He claimed that "illegal immigration costs our country more than $113bn a year", blaming migrants for at least some of the country's economic woes, though they comprise only a tiny fraction of the population - a divisive tactic Trump has long employed to stoke resentment.

That figure, which is derived from a group advocating for limits on immigration, contradicts other studies finding that undocumented immigrants yield a net positive for the economy, by ignoring contributions like the nearly $12bn a year they generate in state and local taxes.

Right way to deal with immigration

Meanwhile, immigration from Mexico has been slowing, not growing at a record clip. Between 2009 and 2014, there was a net loss of 140,000 people, as many Mexicans returned home to reunite with families.

Also, apprehensions of Mexicans at the southern border are decreasing, according to a US Customs and Border Protection Report for 2015 (PDF).

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Trump reiterated his position on Muslim migrants, recast from a total ban to "extreme vetting", that includes an ideological test intended to weed out those who do not share the country's liberal values, including religious freedom, and women's and gay rights.

Under the policy, Trump said previously, "Those who do not believe in our constitution, or who support bigotry and hatred, will not be admitted for immigration into the country."

It is a standard some observers quipped that Trump himself would be hard-pressed to pass.

There is not a consensus in the US about how to deal with those who are not legally in the country, and reasonable minds can differ about a sound and humane policy without being xenophobic.

But Trump's vitriol and demonisation of undocumented immigrants forecloses any constructive dialogue on the issue.

It also ignores the logistical challenges and financial costs of the deportation he promises, the civil liberties his plan would threaten, and the devastation it would wreak upon hardworking families who have long contributed to the nation's diverse social fabric and economy.

If the country really wants to uphold its vaunted ideals of tolerance and compassion, the massive roundup, detention and deportation of immigrants defies those goals.

Lauren Carasik is a clinical professor of law and the Director of the International Human Rights Clinic at Western New England University School of Law.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.