From President Obama and Hillary Clinton on the left, to Donald Trump and Ted Cruz on the right, they all talk about what to do with the "11 million" illegal aliens residing in America.

The Democrats and many in the GOP establishment such as Sen. Marco Rubio and Gov. John Kasich, say it's "unrealistic" to seriously consider deporting the "11 million."

But immigration hawks have scoffed at that figure. In the absence of hard data, they claim the actual number is likely much higher.

William Gheen, president of Americans for Legal Immigration or ALIPAC, for instance, estimates the number at between 12 million and 20 million.

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Arnold Ahlert, a former columnist for the New York Post, goes further in a recent article for Canada Free Press. He portends that the true number of illegal aliens residing in the United States could be 20 to 40 million.

Ahlert says Americans have become numb to the number – 11 million – because it has been used by politicians for more than a decade.

He suggests that if the true number of illegals were ever to be widely reported by the media, the resulting anger of the American public would upset the apple cart in Washington far more than is evident even in the current anti-establishment tide that has swept Donald Trump to front-runner status in the GOP presidential primaries.

"We don’t have to imagine the reaction," Ahlert writes.

He continues:

"Despite what is best characterized as the biggest media disinformation campaign in the history of the republic, millions of Americans are furious at the prospect at having their birthright sold out from under them by Democrats invested in cheap votes, and Republicans invested in wage-depressing labor. And make no mistake: since wide-open borders and visa overstays directly affect the economy, national security and the ultimate character of the nation – one where the rule of law remains paramount, or one that devolves into a Third World banana republic – immigration is the issue in this election cycle."

The Center for Immigration Studies came out with a report this week that estimates the illegal population is 15.7 million if one includes the anchor-babies born to illegals while on U.S. soil.

"That 15.7 million is right in the middle of what we've been saying," Gheen said. "But I think if you count the ones who have been given some sort of status, plus the illegal stock, it's at least 20 million. There are illegal aliens who are going around carrying green cards and work permits right now that by law would still be classified as illegal, but by the Obama administration's new criteria, would not."

A more important number: '1 million a year'

Tom Fitton, president of Judicial Watch, has said he believes an estimate of 12 to 15 million illegals is believable, but to him the more important number is how many immigrants, whether legal or illegal, are arriving in the U.S. annually. This number is not debatable nor does it change depending on the source. That number is 1.1 million per year.

"Eleven million (illegals) is not acceptable to the American people and certainly 15 million raises the price accordingly. But the cutting-edge number we should all be looking at is the mass numbers of non-citizens who have entered the U.S., legally, at a rate of 1 million a year," Fitton told WND.

This is the number that you typically won't hear come up at the presidential debates.

"No one ever voted on that number and I don’t think Americans would approve of that number," Fitton said. "None of the candidates will address that number either because they've all bought into the canard that only illegal immigration is bad."

No country in the history of the world has taken in more than 1 million immigrants per year for any length of time and survived.

While America has always been a "nation of immigrants," there have been periods in which the government, under President Eisenhower for instance, tempered the influx to allow time for the existing immigrants to assimilate.

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And those immigrants were coming from places like Ireland and Germany, whereas today close to half of the 1 million immigrants are coming from the Middle East, Africa and central Asia – a fact that theoretically would make assimilation more challenging and stressful for both the immigrant and his adopted country.

Research from the government's own databases, for instance, indicates that refugees from the Middle East are far more likely to depend on government assistance such as food stamps, Medicaid and subsidized housing.

"No one is making the argument that 1 million new immigrants a year benefits the country," Fitton said. "They don't want to talk about that number because to state that number almost begins and ends the argument."

Having said that, Fitton says he has faith in the research put out by Steven Camarota at the Center for Immigration Studies. CIS updated its research this week with a new report that says there are now a record-high 61 million foreign-born persons living in America, and that figure includes nearly 11 million illegals.

But if you include the children of illegals born in the U.S., the number jumps to 15.7 million, said Camarota, whose numbers are based on data at the U.S. Census, Department of Homeland Security and Pew Research Center.

"In 2015, it looks like 10.5 million illegals are in the data as are 5.1 million of their U.S.-born children for a total of 15.7 million," Camarota told WND. "There is no adjustment for under count. If there were, then the illegals would be more like 11.5. For a total of illegals and their U.S.-born children of 16.7 million."

He adds, however, that if the illegal population is stable in size, it does not mean fewer new illegals are entering the U.S. or overstaying their visas.

"I have estimated that just since Obama became president, 2.5 million new illegal aliens came to America," he said.

"But remember, if 100,000 are given legal status by getting asylum or marrying an American, etcetera, each year and 100,000 are deported and 100,000 go home on their own and 50,000 die, then 350,000 new illegals have to join this population for the total population to remain even."

The government estimates that about 400,000 persons either enter the U.S. illegally or overstay their visas every year.

"It's been hotly debated exact how many," says Gheen. "We've been telling people 12 to 20 million for the last 12 years. The U.S. Census and other government agencies estimate 11 to 12 million, but Barron's and other private firms have a higher number. But also it's hard to say how many illegals are in the country now because the Obama administration has been making many of them quasi-legal."

Fitton said it is no accident that immigration is the driving issue in the Republican primary election for president.

"The large number of illegals entering the U.S. is not only the fault of the president and the Republican majority that's enabled it, but him talking about amnesty results in more illegal immigration," he said.

"If you enter the U.S., unless you were just unlucky enough to be one of the few caught and returned, the Obama administration, with the full support of the GOP establishment, is refusing to deport any illegal alien who hasn't committed a felony, and committing a murder is no guarantee of removal, so the crisis continues and we are literally losing a country. A slow motion invasion."