President Obama and Secretary of Education Arne Duncan are ramping up efforts to build public support for a way to prevent the interest rate on some student loans from doubling in July.

The interest rate on subsidized Stafford loans is set to double, from 3.4 percent to 6.8 percent, on July 1. The change would affect more than seven million student-loan borrowers, who would incur an extra $1,000 in annual interest charges for each loan, according to Mr. Duncan.

After visiting colleges in Wisconsin and Iowa on Thursday, Mr. Duncan spoke at a White House briefing on Friday to promote the seemingly quixotic task of persuading Republicans in Congress to preserve the lower interest rate.

"At a time when college has never been more important, it also, unfortunately, has never been more expensive," he said at the briefing. "Our administration is doing more than ever before to address it."

For his part, the president will make stops next week at flagship public universities in Colorado, Iowa, and North Carolina—which also happen to be swing states in the presidential election—to press this issue...