More illegal immigrants have been expelled from the United States during Barack Obama’s presidency than ever before. Since 2009, the Obama administration has removed 2.5 million people from American soil — an enormous crackdown that has consumed an enormous amount of money. The federal government now spends more on border and immigration enforcement than it spends on all other criminal law-enforcement agencies — including the FBI, the Drug Enforcement Administration, the Secret Service, the US Marshals Service, and the Bureau of Alcohol, Tobacco, Firearms and Explosives — combined.

So many aliens have been removed on Obama’s watch that critics ranging from The Economist to La Raza have dubbed him the “deporter-in-chief.”

But if Donald Trump or Ted Cruz get their way, you ain’t seen nothing yet.

Trump tells voters that as president he will eject undocumented aliens “so fast that your head will spin.” When asked how long he would need to remove all of the estimated 11.3 million illegal immigrants living in the country, he has said it should take no more than “18 months to two years if properly handled.”

Cruz also wants to kick out all unlawful immigrants. “Yes, we should deport them,” he told a TV interviewer. “Anyone here illegally that’s apprehended should be deported.” Cruz’s campaign website dismisses the millions removed under Obama as merely “a fraction of what we could accomplish if we had a President who actually forced DHS [the Department of Homeland Security] to do its job.”

The eviction of more than 11 million immigrants, the overwhelming majority of whom are peaceful and productive, is a mad idea. Polls consistently show that Americans oppose mass deportations. A president attempting to carry out such a policy would unleash a frightful wave of social and political turmoil.

Then there are the fiscal costs.

The American Action Forum, a center-right think tank headed by economist Doug Holtz-Eakin (former director of the Congressional Budget Office), calculated last year that to expel all undocumented immigrants living in the United States would take 20 years and cost the federal government at least $400 billion in extra spending. Now, in a new study, the think tank details the enormous increase in resources that would be needed to pull off such a massive population transfer in just two years.

Evicting immigrants is a four-step process. They must be apprehended, detained, prosecuted, and transported. To track down and apprehend unlawful immigrants, the federal government currently employs 4,800 immigration-enforcement officers. But the US Immigration and Customs Enforcement (ICE) would need more than 90,000 enforcement agents in order to apprehend millions of illegal aliens in just two years.

Today, arrested aliens are detained in 250 detention facilities, which hold about 34,000 people at any given time. But a two-year detention timetable would necessitate a tenfold increase in capacity — the number of detention facilities would have to soar to more than 2,500, with beds for 348,000. The government would also need far more than the 58 immigration courts that currently adjudicate removal cases; the report estimates that another 1,258 courts would have to be established, and another 30,000 government attorneys hired.

Even more staggering is the equipment that would be required to deport everyone within two years. The 1,400 chartered flights needed annually for deportations now would skyrocket to more than 17,000. The 2,500 bus trips would explode to 30,000.

And when all the illegal migrants were gone, America would find itself reeling from a self-inflicted economic wound. The elimination of 6.4 percent of the US labor force would wipe out $1 trillion in economic activity. Two years into the next president’s term, we would be mired in another deep recession, more painful than the last one.

Mass deportations would leave America poorer, its government more swollen, and its social fabric in tatters. Americans will never go along with such destructive idiocy, no matter whom they choose as president.

Jeff Jacoby is a columnist for The Boston Globe.