Seven million students are about to get a tough lesson in economics.
Interest rates on student loans subsidized by the government will most likely double to 6.8 percent on July 1.
The increase will only affect one-third of all undergraduate students who have subsidized loans that are awarded based on economic need.
Undergraduates with unsubsidized loans have been paying 6.8 percent since 2007.
Congress and the White House agree something should be done to prevent the increase -- they just don't agree on how to do it.
The Republican-controlled House passed a bill last week that would stop the rates from doubling now, but would allow them to rise later.
President Obama vowed to veto it, calling it the "wrong approach."