U.S. Secretary of State John Kerry said on Saturday he hoped it would be possible to reach an interim deal with Iran "in the next days" if Tehran can show that its nuclear power program is for peaceful purposes only, according to Reuters.
Speaking ahead of fresh talks with Iran in Lausanne, Switzerland, schedule to begin on Sunday, Kerry appeared more upbeat about the possibility of a framework agreement by a deadline at the end of the month. The deadline for a final agreement is June 30.
Earlier on Saturday he told a news conference on the sidelines of a conference in the Red Sea resort of Sharm El-Sheikh that it was unclear whether an interim deal was within reach.
A deal would curb Tehran's most sensitive nuclear activities for at least 10 years in exchange for the gradual easing of some sanctions.
"We believe very much that there’s not anything that’s going to change in April or May or June that suggests that at that time a decision you can’t make now will be made then," Kerry was quoted as having told CBS News.
"If it's peaceful, let's get it done. And my hope is that in the next days that will be possible," he added.
Iran and the six world powers are trying to turn an interim 2013 deal into a permanent agreement.
Under the interim deal, Iran committed to limit its uranium enrichment to five percent and is gradually winning access to $4.2 billion of its oil revenues frozen abroad and some other sanctions relief.
Talks to reach a permanent deal have continuously stalled and two deadlines for a final deal have been missed.
On Friday, a senior European diplomat said that while nuclear talks between Western powers and Iran have made progress, some very difficult issues remain.
In the CBS interview, Kerry was asked about the letter written by 47 Republican senators to Iran last week, threatening to undo any Iran deal once President Barack Obama leaves office.
The letter was written by Tom Cotton, a first-term senator from Arkansas, who has often criticized Obama's foreign policy.
Asked whether he would apologize for the letter when he meets with Iranian Foreign Minister Mohammad Javad Zarif on Sunday, Kerry responded, "Not on your life."
"I’m not going to apologize for an unconstitutional, un-thought out action by somebody who’s been in the United States Senate for 60-something days," he declared. "That's just inappropriate."
He said he would explain to Iran's negotiators and other world powers involved in the talks that Congress does not have the right to change an executive agreement, as he indicated last week when he addressed the Senate Foreign Relations Commitee.