Fox Business Network host Lou Dobbs, left, speaks with Bill O'Reilly during a 2009 interview. (Kathy Willens/AP)

Lou Dobbs said it so casually that it sounded like common knowledge.

“You know,” the Fox Business Network host said on his show Thursday, “millions of illegal immigrants cross our borders, and many of them [were] voting in the past election that’s what, just a couple weeks ago, and having an immense impact.”

Dobbs later asked, “Are we just sitting here, helpless against anyone who wants to cross that border, and to have their way with the American way?”

He was chatting with David N. Bossie, a former deputy Trump campaign manager.

Since the midterm elections, no evidence has emerged suggesting results were tainted by illegal votes, from illegal immigrants or anyone else.

The statement was par for the course for Dobbs, who was bashing immigrants before it was fashionable, citing misleading evidence or none at all. Last month, he invoked the word “invasion” dozens of times on his program when talking about the migrant caravan, according to NPR, parroting the same language used by President Trump.

Dobbs didn’t even pretend to have evidence of the illegal voting Thursday night. He just said it, apropos of nothing, during his show, “Lou Dobbs Tonight.”

He referred to a recent study from Yale and MIT, the reliability of which has been questioned by other researchers: “If there are, as Yale and MIT say, 20 to 30 million illegal immigrants already in this country,” Dobbs said, “you know what that means for the districts of the U.S. Congress and the influence that they’re giving to, for example, the state of California, Illinois, New York.”

Dobbs, according to Forbes, is “the most-watched host in business television.” He has a following of hundreds of thousands of viewers and 1.85 million Twitter followers.

Before joining Fox Business Network, Dobbs built his career at CNN by blaming illegal immigrants for everything from deadly disease to a significant portion of the nation’s crime. His take on border security once led the New Yorker’s satirist Andy Borowitz to jokingly write that former president George W. Bush, “in his toughest stand yet against illegal immigration,” sent Dobbs to the border to fend off border crossers in lieu of 10,000 troops from the National Guard.

While at CNN, Dobbs said an “army of invaders” from Mexico was crossing the border illegally as part of a plan to “take over” the southwestern United States. He has misleadingly said undocumented immigrants comprise one-third of the federal prison population. And perhaps most notoriously, Dobbs said in 2005 that an “invasion of illegal aliens is threatening the health of many Americans,” before turning to a report wrongly finding that, despite there being only “900 cases of leprosy for 40 years,” there had been “7,000 in the past three years.”

“Incredible,” Dobbs said. In fact, there had been 7,000 leprosy cases in the last 30 years. When Lesley Stahl of “60 Minutes” confronted him about the assertion two years later, telling him there appeared to be no evidence to support the claim, Dobbs stood his ground. “Well, I can tell you this,” he said. “If we reported it, it’s a fact.”

He abruptly resigned from CNN in 2009 after Jonathan Klein, then the president of CNN, gave him an ultimatum: tone down the rhetoric or leave. When he quit, he toyed with the idea of running for president.

More recently, Fox Business Network found itself apologizing for Dobbs. The network pulled an October episode of “Lou Dobbs Tonight” in which the host’s guest, Chris Farrell of Judicial Watch, said the migrant caravan was being funded by the George “Soros-occupied State Department.” There was no pushback from Dobbs and Fox Business soon “condemn[ed] the rhetoric” in a statement.

A spokesman for Fox Business Network did not immediately return a request for comment regarding Dobbs’s latest assertion.

The comment recalls Trump’s baseless assertion after the 2016 presidential election that 3 million to 5 million illegal votes cost him the popular vote. Dobbs told The Washington Post then that he believed the president’s critics and the news media rushed to judgment when reporting the president’s statement was false.

“You cannot say the president has made a false statement when he says there are 3 to 5 million illegal votes, in his judgment,” Dobbs told The Post. “We don’t know on what basis he made the claim. But we do know this: It’s speculative, and therefore it is a good thing because all he is asking for is an investigation of it and is pursuing it.”

No evidence was ever found to support the claim.

Aides for Trump — who most recently claimed without evidence that people were changing into different clothes and hats in their cars in the parking lots of polling places to disguise themselves and vote twice — pointed to research from Old Dominion University to support the mass illegal voting assertion in 2016. The study, which has been challenged by other researchers, found 14 percent of noncitizens were registered to vote. But its authors warned it was impossible to extrapolate that to represent the entire population of noncitizens.

As The Post has reported, even if it were possible to extrapolate the data, and even if, in that hypothetical world, all 14 percent of those noncitizens voted at the same rate as citizens, that would still account for just 1.1 percent of all votes.

Dobbs, in his interview with The Post about Trump’s 2016 illegal voting claims, said he hoped Trump “would consider me a friend and supporter.” Such an ardent supporter of the president, he once had to apologize for doxing a woman who accused Trump of sexual assault after he posted her phone number and address on Twitter.

Dobbs has been described as “one of the main precursors to Trumpism.” He’s also friends with Trump, who reportedly loves his show. The Daily Beast, citing sources, reported in April that “Dobbs doesn’t get to just interview and socialize with the president; he is involved in some of the administration’s more sensitive discussions. During the first year of the Trump era, the president has patched in Dobbs via speakerphone to multiple meetings in the Oval Office so that he could offer his two cents.”

In return, Trump regularly quotes and promotes Dobbs’s show.