The mass shooting of Muslim worshippers by an alleged white supremacist in New Zealand has underscored the deep partisan divide over President Donald Trump's rhetoric on immigrants and whether his words serve as incitement for extremist violence.

Mick Mulvaney, the acting White House chief of staff, said it was "absurd" to draw a connection between Trump's many statements about immigration and the suspected shooter's own words on the subject, spelled out in a lengthy manifesto that referred to immigrants as "invaders within our lands" and called Trump "a symbol of renewed white identity and common purpose."

Speaking on "Fox News Sunday," Mulvaney said, "I don't think it's fair to cast this person as a supporter of Donald Trump any more than it is to look at his eco-terrorist passages in that manifesto and align him with (House Speaker) Nancy Pelosi or (Rep. Alexandria) Ocasio-Cortez."

The suspect, Brenton Harrison Tarrant, described himself as an "ethno-nationalist eco-fascist" in his lengthy, discursive statement, but he rooted that in his nationalist philosophy, accusing politicians on the left of "presiding over the continued destruction of the natural environment itself through mass immigration and uncontrolled urbanization ..."

Mulvaney said, "There are folks who just don't like the president and everything that goes wrong they're going to look for a way to tie that to the president."

"The president is not a white supremacist," he added later, responding to critics who accused the president of echoing the suspected gunman's rhetoric in comments from the Oval Office hours after the massacre.

Announcing his veto of a congressional resolution that would block his declaration of a national emergency at the U.S. border with Mexico, Trump called the movement of undocumented immigrants into the United States an "invasion."

"Last month, more than 76,000 illegal migrants arrived at our border," he said. "We're on track for a million illegal aliens to rush our borders. People hate the word 'invasion,' but that's what it is."

Mulvaney also sought to distance Trump from Tarrant, noting that while the avowed white supremacist called Trump an inspiring figure, he also wrote that he didn't view him as an effective "policy maker and leader."

"Dear god no," Tarrant wrote.

Scott Brown, the U.S. ambassador to New Zealand, dismissed Tarrant's manifesto and encouraged people not to read it. "I don't give any credibility whatsoever to the ramblings of somebody who is rotten to the core and, clearly, is an extremist of the worst kind, who could walk into two mosques and, without any care whatsoever, kill people," Brown said on CNN's "State of the Union."

Others on Sunday denounced Trump's response to the attack. On Friday, Trump said that he does not believe white nationalism is a growing global danger and that the suspect belongs to "a small group of people that have very, very serious problems."

On CNN's "State of the Union," Rep. Rashida Tlaib, D-Mich., one of three Muslim lawmakers serving in the House, urged Trump to deliver a message of support to the Muslim community in the wake of the New Zealand attack.

Trump "is the most powerful man in the world right now," Tlaib said, urging him to speak out about domestic terrorism to the same degree that he has about foreign terrorism. "The fact that we continue to stay silent is what's going to make us as a country less safe."

She also disputed Trump's claim that white nationalism is not on the rise.

"I think he needs to pick up the phone and call the Department of Justice. ... He cannot just say it's a small group of people. There's too many deaths," Tlaib said, pointing to recent attacks on worshipers at synagogues, black churches and mosques. "He needs to do better by us in the country."

Sen. Amy Klobuchar, D-Minn., a 2020 presidential candidate, also urged Trump to take a stronger stand against anti-Muslim bigotry.

"At the very least, he should be giving strong statements, public speeches defending Muslims in this world," Klobuchar said on "State of the Union." "I think it's on all of us to condemn this hate."