WASHINGTON — Celebrating the ethnic diversity of America, President Barack Obama said more than two dozen foreign-born service members who became U.S. citizens at the White House on the Fourth of July are vivid reminders that welcoming immigrants “is central to our way of life.”

He pleaded anew for new immigration policies, saying the vast range of backgrounds and experiences that has made America a melting pot for more than 200 years also makes the country stronger. He argued that the system must be retooled for the U.S. to remain the greatest nation on earth.

“The basic idea of welcoming immigrants to our shores is central to our way of life, it is in our DNA,” Obama said after the 25 service members representing 15 countries raised their right hands and pledged allegiance to the United States.

“From all these different strands, we make something new here in America. And that’s why, if we want to keep attracting the best and brightest from beyond our borders, we’re going to have to fix our immigration system, which is broken,” he said. “Pass common-sense immigration reform.

The immigration issue is earning renewed attention because of the influx to the U.S. of tens of thousands of unaccompanied children from Central America. Under U.S. law, they must be returned to their home countries, angering immigration advocates who already take issue with Obama’s enforcement of deportations. They want Obama to allow the children to stay.