Child migration is surging again.

The number of families and unaccompanied children apprehended on the southern border has skyrocketed this year, according to new figures from the Obama administration.

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The numbers, compiled by the U.S. Customs and Border Protection (CBP), reveal that child migration is on par with 2014 levels, when a wave of kids — thousands of them unaccompanied — arrived at the southern border.

The surge of illegal immigration quickly swamped border authorities, immigration courts and health and humanitarian workers, while sparking a political battle on Capitol Hill over the cause and proper response to the crisis.

The new figures raise the specter of another increase this summer. That would almost certainly inflame another political showdown in a volatile presidential year in which the issues of race, immigration and border security have been pronounced — particularly due to the hard-line enforcement approach adopted by the presumptive GOP nominee Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE.

Through the first six months of fiscal 2016, which ended on March 31, border officials apprehended 27,754 unaccompanied children, the CBP reported — a 78 percent jump from the 15,616 apprehended in 2015, and just shy of the 28,579 apprehended in 2014.

For family units, which consist of at least one child traveling with at least one adult, the increase was even more dramatic. In the first six months of 2016, 32,117 families were apprehended, the CBP reported — an increase of 131 percent from the 2015 figure (13,913) and 62 percent from the 2014 figure (19,830).

Kevin Appleby, director of international migration policy at the Center for Migration Studies, proposed several reasons for the increase. For one, the violence plaguing Central America — particularly El Salvador, Honduras and Guatemala — still exists, he noted, sending people fleeing north for their lives.

"The forces driving the migration are still strong," he said.

Appleby also suggested the human smugglers accompanying the migrants might have adapted to a crackdown by Mexican authorities in 2015, allowing the smugglers to elude capture and get more people to the U.S. border.

Appleby, along with many other human rights advocates, has been critical of Mexico's policing efforts, and the Obama administration's support of them. They fear that many people eligible for asylum in the United States never make it that far, but are instead returned by Mexican authorities to dangerous conditions in Central America.

"Our policy of deterrence is clearly not working no matter how much we pay the Mexican government to do our dirty work," Appleby said Wednesday.

It's unclear if the 2016 increases will continue into the summer and rival the surge total of 2014. The Obama administration has scrambled to prevent a similar crisis since then, and Congress last year approved $750 million to help stabilize El Salvador, Guatemala and Honduras in hopes of slowing the flow of people trying to come to the U.S.

In January, the Homeland Security Department tried another deterrent strategy, launching a series of controversial raids on scores of families that had arrived in the 2014 surge and putting them in line for deportation.

Jens Manuel Krogstad, of the Pew Research Center, noted Wednesday that the strategy might have worked.

"This fiscal year, family and unaccompanied children apprehensions spiked in December 2015, and in January 2016 the Department of Homeland Security launched immigration raids targeting families," Krogstad wrote on Pew's blog. "Since then, monthly border apprehensions have dropped below 2014 levels."