WATCH: GOP senator warns 'hammer-and-sickle' politics will define Democrats' 2028 primary

FIRST ON FOX: One Senate Republican warned that the "radical leftist" surge in the Democratic Party today will be the roadmap for Democrats in 2028, when candidates will jockey for the White House.

"You get this hammer-and-sickle wave we saw in New York — that is not going to be an isolated incident," Sen. Eric Schmitt, R-Mo., told Fox News Digital. "That is a flashing red light. It is a red flag."

"Their primaries now are going to be dominated by these people who want to go to war with Western civilization," he continued. "I mean, I'm not making this up, this is what they say they want to do. And so their [2028] presidential primary will be defined by this ideology."

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Several insurgent progressive and far-left candidates have toppled more moderate incumbents in primary contests during this midterm election cycle. In New York City, as Schmitt pointed out, Mayor Zohran Mamdani’s chosen candidates made a clean sweep in June.

Two incumbents, Reps. Dan Goldman, D-N.Y., and Adriano Espaillat, D-N.Y., were felled by progressives with the Mamdani stamp of approval — Brad Lander and Darializa Avila Chevalier, respectively.

And in the race for the majority in the Senate, one of the most notable far-left candidates is Abdul El-Sayed in Michigan, who is locked in a messy primary fight with Rep. Haley Stevens, D-Mich.

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Schmitt contended that it was Democrats’ position on immigration, in particular, that was defining their policies and candidates moving forward.

"I think they've just decided that their only chance of being successful electorally is through their immigration policy, and so, they've completely dismissed the arguments of Bill Clinton and even Harry Reid," Schmitt said. "I mean, it sounds crazy to even say that, but they were at least, I guess what you would make a centrist argument on that they've totally abandoned."

Specifically, Senate Democrats are bucking an old policy that was once championed by former Senate Majority Leader Harry Reid, D-Nev. In the 1990s, Reid pushed legislation that would have changed birthright citizenship — just like how Schmitt and other Republicans are doing now after the Supreme Court’s decision upholding birthright citizenship earlier this month.

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Schmitt said Senate Minority Leader Chuck Schumer, D-N.Y., who was mentored by Reid, was on notice by his own party given the further left the political winds were blowing.

His main political adversary could be one of the poster children of the progressive movement: Rep. Alexandria Ocasio-Cortez, D-N.Y.

"You know, Chuck Schumer, if he survives to even be minority leader again, you know, next term, there's just no way he's not going to have a primary challenge by AOC or somebody else," Schmitt said.

"I mean, I think he's probably going to chair the ‘AOC for president campaign’ so … she doesn't run against him, but there's going to be somebody else. And the money and the energy on the Democrat side right now are these radical leftist communists."