For over a year, it's been the centerpiece of his campaign.



But, in a stark midcourse correction on his immigration policy, Republican nominee Donald Trump this week backed away from a pledge to round up millions of undocumented immigrants and transport them outside the country.

In the end, the plan may have simply proved too costly — both politically and economically.

By one estimate the direct price tag for removing some 11 million undocumented workers could top $600 billion. And the economic impact of a such a sudden contraction in the U.S. labor force would lop $1.6 trillion from the nation's economy. That's roughly the gross domestic product of Texas.

From the day he announced his bid for the White House, Trump has made immigration a major focus of his campaign.

"They're sending people that have lots of problems, and they're bringing those problems with us," he said in the day he announced in June 2015. "They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people."