WASHINGTON – Arizona Sen. Jeff Flake penned an opinion piece for Politico deriding President Trump and the new populist, nationalist movement that propelled the GOP into the White House.

In Flake's piece, titled "My Party Is in Denial About Donald Trump," the senator lays out a list of grievances against the president.

Flake denounces "playing to the base" protectionist trade policies and puts his support behind "institutions and prerogatives, like the Senate filibuster."

In his new book, "Conscience of a Conservative: A Rejection of Destructive Politics and a Return to Principle," Flake also embraces the "globalist moniker," denouncing pro-Trump Republicans as "xenophobic" and "nativist."

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Flake was a major proponent of the so-called Gang of Eight's failed attempt to pass "comprehensive immigration reform" that would give amnesty to illegal aliens.

Chris Buskirk's "American Greatness: How Conservatism Inc. Missed The 2016 Election & What The D.C. Establishment Needs To Learn," explains how pro-worker, pro-citizen and pro-America policies can work.

According to one critic, Flake is everything wrong with the Republican Party, promoting many of the objectives of "the left."

Chris Buskirk, the pro-Trump author of "American Greatness: How Conservatism Inc. Missed The 2016 Election & What The D.C. Establishment Needs To Learn" and a proponent of pro-worker, pro-citizen policies, blasted Flake in an interview with WND.

"Jeff Flake has demonstrated time and time that he out of touch with historical American conservatism and with his own constituents. Most voters, especially Republicans, want to see our immigration laws enforced, they want to see American citizens protected," Buskirk said.

Buskirk continued: "Jeff Flake was part of the Gang of 8. He's for amnesty. He calls enforcement of our immigration laws 'nativism' and 'xenophobia.' When Donald Trump was talking about draining the swamp, that was part of it."

To Buskirk, Flake's statement that "we shouldn't hesitate to speak out if the president 'plays to the base" shows a complete disregard for the voters that put Republicans in power.

"He's saying that he and people like him are the true conservatives and not Trump's voters," Buskirk said. "That's just wrong. The Trump agenda of America First foreign policy, pro-citizen immigration policy, and pro-worker trade policy are conservative – and always have been."

According to Buskirk, rather than rely on Republican voters, Republicans such as Flake simply pander to Democrats.

"Jeff Flake, like John McCain, relies on Democrat votes to stay in office," he said.

"The conservative base is furious with Flake who plays the same game so many politicians play by siding with the New York Times and Joe Scarborough until a few months before election time and then quickly tacking to the right so they can pretend they care about what matters to voters," Buskirk said.

He believes Flake's portrayal of himself as a "principled conservative" who is true to conservative ideals could not be further from the truth.

"What are Jeff Flake's conservative principles? I don't see them," he said.

"The agenda that 63 million Americans voted for in November is consistent with American conservative principles. Forsaking the interests of citizens, denigrating voters and trying to undermine the results of elections is not a conservative principle," Buskirk added.

Buskirk is particularly disheartened by Flake's pro-amnesty stance and believes embracing such policies would be the death knell of the Republican Party.

"Conservatives voters won't support amnesty. When Republican politicians support amnesty they suppress Republican turnout at election time because so many stay home out of disgust. What's more, undermining the rule of law and allowing a large body of people to enter and remain in the country is a threat to the integrity of our electoral system," Buskirk opined.

Buskirk believes the left understands this, which is why Democrats "support allowing illegal aliens to get drivers licenses, registering to vote by mail, and registering to vote on the day of the election."

"Sadly, many establishment Republicans don't care about protecting American citizens or enforcing the law," Buskirk concluded.

While Flake suggests the path forward for the Republican Party is to reject President Trump, Buskirk believes the opposite.

"Republicans should support their president and enact his agenda. Period. We should repeal Obamacare, reduce taxes, defend the border, and promote the interests of the middle class."

Buskirk's message is ultimately simple: The party can survive only by embracing what Republican voters want.

Chris Buskirk's "American Greatness: How Conservatism Inc. Missed The 2016 Election & What The D.C. Establishment Needs To Learn", explains how pro-worker, pro-citizen and pro-America policies can work.