During President Eisenhower’s first term, 60 years ago, the United States faced an invasion across its southern border.

Illegal aliens had been coming since World War II. But, suddenly, the number was over 1 million. Crime was rising in Texas. The illegals were taking the jobs of U.S. farm workers.

Under Gen. Joseph May Swing, the Immigration and Naturalization Service launched “Operation Wetback” and began rounding up and deporting Mexican border-crossers by ship and bus. By the end of Ike’s second term, illegal entries had fallen by 90 percent.

Eisenhower, who had tapped his nuclear hole card twice—first, to force the Chinese to agree to a truce in Korea, then to halt their shelling of the offshore islands in 1958—was a no-nonsense president.

Measured by population and gross national product, Eisenhower’s America was but half the size of today’s America. Yet, in the 1950s, we were in many ways a stronger and more self-confident country.

We had universal military service, and few complained. As for the deportation of the Mexicans, they had broken in, they did not belong here, and they were going back. End of discussion.

Contrast the rigorous response of Ike’s America to an invasion across our southern border to the hand-wringing moral paralysis of our political elite in dealing with 11-12 million illegal aliens in our midst.

We are to stop using terms like illegal aliens, we are told. For it shows insensitivity. And compassion commands that we bring these folks “out of the shadows” and “put them on a path to citizenship.”

One understands Democrats’ motives in pushing this amnesty. Perhaps nine of 10 illegals are from Third World countries, and folks of Asian, African and Hispanic descent voted 4-to-1 Democratic in 2012.

Sen. Chuck Schumer and Democrats are writing an immigration bill that will create millions of new citizens who will vote to bury the Party of Ronald Reagan forever.

But why are Republicans collaborating in erecting the scaffolding on which their party is to be hanged?

A year ago, the GOP platform declared, “We oppose amnesty because it would have the effect of encouraging illegal immigration and would give an unfair advantage to those who have broken our laws.”

What has changed since then?

Yet, today, with Cuban-American Sen. Marco Rubio providing cover—a “very positive force,” purrs President Obama—Republicans are about to trash their platform and vote an amnesty for 11-12 million illegals. Why?

One reason is the fear, bordering on panic, since Mitt Romney lost the Hispanic vote 71 to 27. Republicans attribute their unpopularity among Latinos to their opposition to amnesty, rather than their commitment to peel back the social programs on which minorities heavily depend.

Another force for amnesty is corporate America. Thousands of businesses have hired illegals in violation of U.S. law. Amnesty for their illegal workers means, de facto, amnesty for them.

Moreover, U.S. corporations and agribusiness also want the right to import foreign workers. And under this new immigration bill, H1-B visas for highly skilled engineers and computer programmers will double to 110,000 a year, and the cap can rise to 180,000. Visas for H-2A agricultural workers will go to 337,000 over three years.

Silicon Valley is not interested in middle-aged Americans who lost jobs in defense industries. They want young foreign students with newly minted advanced degrees, who will work for less.

Thus, with 14 percent of our U.S. labor force—more than 21 million Americans—unemployed, working part-time but seeking full-time work or having stopped looking, Congress is going to vote an amnesty for 12 million illegals and bring in a million new immigrants a year—and hand them green cards.

What happened to putting our own country and people first?

Moreover, under the new law, unlimited visas will be issued for spouses, children and parents of permanent residents and citizens.

With all these workers and dependents pouring in, the downward pressure on U.S. wages, stagnant since Gerald Ford was president, will intensify. And the steady rise in the scores of millions of beneficiaries of social welfare programs will continue.

What do Republicans get in return for capitulating and embracing amnesty? The Democrats solemnly promise to secure the border this time.

In short, the administration will do its duty and protect the states from another invasion, if the Republican Party will abandon its principled opposition to amnesty. The Republicans will be faithless to those who voted for them on a pledge not to support amnesty, if only Obama will promise a good-faith effort to do his constitutional duty.

Prediction: Once word goes out that the illegals will no longer be sent back, there will commence a new stampede to the border.

And once the new law is on the books, Democrats will move to truncate the time for the former illegals to become U.S. citizens.

And Republicans who resist will be accused of being anti-Hispanic, and will then do what comes naturally—capitulate again.