WASHINGTON: The Obama administration’s chief nuclear negotiator refused Tuesday to provide a hard deadline for a deal with Iran to prevent it from developing nuclear weapons. She vowed to consult with Congress before suspending more economic sanctions on Tehran, but said the administration won’t necessarily seek lawmakers’ approval.

The testimony by the State Department’s Wendy Sherman immediately prompted objections in the Senate Foreign Relations Committee, whose Democratic and Republican members pushed for clear markers as part of the diplomatic effort. World powers and Iran recently committed to a four-month negotiating extension through Nov. 24, an agreement that allows the Islamic republic to recoup $2.8 billion in Iranian assets frozen in overseas bank accounts.

“The next four months will allow us to determine whether a diplomatic solution is possible,” Sherman told the panel. “A comprehensive resolution, if we are able to arrive at one, will benefit people everywhere. It will ease anxiety and enhance security throughout the Middle East. It will reduce the likelihood of a nuclear arms race in the region. It will eliminate the potential threat of nuclear blackmail. It will contribute to the security of Israel, the Gulf states and our partners throughout the region.”

But pressed by senators to outline how long the administration would continue talking and how far it would consider bending to coax Tehran into an accord, Sherman refused to be pinned down. She wouldn’t promise the current extension would be the last. She said the administration would consult lawmakers before waiving more sanctions, but doesn’t need their approval.

Sen. Bob Corker of Tennessee, the top Republican on the committee, described Sherman’s pledge as a “zero commitment.”

Sen. Marco Rubio, R-Fla., was blunter.

“This entire thing is a disaster,” he said.