Pollster Lee Miringoff told Hill.TV in an interview that aired Thursday that "Never-Trump" Republicans are essentially extinct.

"The 'Never Trumpers' have vanished in the Republican Party. They're extinct," Miringoff, the head of the Marist Poll, told Hill.TV's Joe Concha on "What America's Thinking."

Various "Never Trump" conservatives, however, frequently appear on cable news to advocate against Trump's presidency, including Bill Kristol, Ana Navarro, and David Brooks.

Trump has enjoyed high approval ratings among Republicans, with 86 percent saying they approved of his job as president according to a recent Gallup poll.

Republicans have pointed to a number of Trump's achievements, including the passage of the GOP tax law and his appointment of two conservative Supreme Court justices as reasons for supporting him.

GOP voters have also expressed optimism in the current state of the economy, which many have said is a direct result of Trump's economic policies.

Trump and his Republican base last month touted news of the unemployment rate falling to 3.7 percent, a 49-year low, while the economy added 134,000 jobs.

— Julia Manchester