Sen. Jeff Flake announced that he would not be backing President Donald Trump’s nomination of Ronald Mortensen to be assistant secretary of State for population, refugees and migration.

Flake, an Arizona Republican and member of the Foreign Relations Committee, linked his opposition to a Politico report about some of Mortensen’s well-documented views about immigration.

“This nominee will not have my support,” the senator said Tuesday night.

This nominee will not have my support https://t.co/qnPqVCS3tG

— Jeff Flake (@JeffFlake) May 30, 2018

Mortensen, a fellow at the Center for Immigration Studies, has often directly attacked senators like Flake who have supported bipartisan immigration overhaul efforts.

In a February 2017 post on the CIS website, Mortensen alleged that Flake “wants illegal aliens who commit identity theft and other serious crimes that do real harm to their American victims to be able to stay in the United States.”

He was citing comments made during an appearance on the CBS News program “Face the Nation,” with then-moderator John Dickerson, in which Flake said most undocumented individuals generally comply with the law.

Flashback: Flake Condemns Trump’s Attacks on Media

“Maybe Flake should provide his and his family’s Social Security numbers to illegal aliens since he obviously doesn’t think identity theft and Social Security fraud are serious crimes,” Mortensen wrote. “Based on this interview, it is clear that Dickerson and Flake are illegal alien crime deniers and that they are complicit in creating a fake news narrative.”

The White House did not respond to a request for comment on the Mortensen paper trail even before Flake formally announced his opposition to the nominee.

Mortensen criticized Arizona Republican Sen. John McCain in 2015 under the headline, “McCain Rolls Out the Welcome Mat for ISIS on America’s Southern Border.”

“While assertions that ISIS is pre-positioning or has already crossed the southern border may be challenged, what is certain is that McCain has provided ISIS with unfettered access to the United States for both its personnel and their weapons of death and destruction,” Mortensen wrote. “Should ISIS or some other terrorist group take advantage of McCain’s welcome mat, he will only have himself to blame as he goes in the eyes of many from war hero to collaborator.”

With only a one-seat GOP majority on the Foreign Relations Committee, Mortensen would need the support of at least one Democrat to prevent an adverse report — if the committee even considers him at all.

But that might not happen because Mortensen has also directed criticism at Chairman Bob Corker of Tennessee over his amendment with North Dakota Republican Sen. John Hoeven to the 2013 Senate immigration bill.

John T. Bennett contributed to this report.