US Deputy National Security Advisor Tony Blinken has told lawmakers that it will be “difficult” for Washington and other powers to reach a nuclear agreement with Iran before next Monday, the deadline set for finalising the negotiations.

“Right now, I think it’s going to be difficult to get to where we want to go. It’s not impossible,” Blinken, President Barack Obama’s pick to be deputy secretary of state, said at the Senate Foreign Relations Committee nomination hearing Wednesday.

Reaching an agreement “depends entirely on whether Iran is willing to take the steps it must take to convince us, to convince our partners, that its programme would be for entirely peaceful purposes. As we speak, we’re not there”, he said.

Blinken said the latest negotiating round has been underway since Tuesday in Vienna, and the talks could change from “minute to minute”. So, it was not known whether or not a deal could be struck before the deadline.

He did not want to speculate on the chances for extending the Nov 24 deadline, which had been set before the talks got underway a year ago.

Secretary of State John Kerry is scheduled to travel to Vienna at the end of next week to join the meetings that began Tuesday with Iranian Foreign Minister Mohammad Yavad Zarif and the former top European Union foreign policy official, Catherine Ashton.