WASHINGTON (AP) — The Obama administration's nuclear negotiator is refusing to impose a hard deadline for a deal with Iran to prevent it from developing nuclear weapons.

World powers and Iran recently committed to a four-month negotiating extension through Nov. 24.

Testifying before the Senate Foreign Relations Committee, Wendy Sherman says she won't call that a make-or-break date.

She also says the administration will consult with Congress before suspending any more sanctions on Iran.

But Sherman says U.S. officials don't need congressional approval to do so.

Republican Sen. Bob Corker of Tennessee expressed disappointment at Tuesday's hearing, calling Sherman's pledge a "zero commitment."

Iran says its nuclear program is for energy and medical research. The U.S. and its partners suspect it's a covert weapons program.