WASHINGTON - Interest rates on new student loans have doubled because the Senate did not plan a vote before Monday's deadline.

The chairman of the Education Committee and other Democrats said last week that the Senate would vote on July 10 on a one-year extension of the current interest rates. Without congressional action, rates on subsidized Stafford loans have gone from 3.4 percent to 6.8 percent.

Iowa Sen. Tom Harkin says lawmakers could pass a bill that retroactively lowers rates. A previous attempt in the Senate to extend rates for two years failed to overcome a procedural hurdle. The House has already passed a student loan proposal.

AP wire services contributed to this report.