On the eve of the latest in a string of deadlines for the conclusion of talks on Iran's nuclear program, a resolution seemed to be just out of reach of negotiators.
U.S. Secretary of State John Kerry said Thursday if difficult decisions are not made in Iran nuclear discussions, negotiators are ready to "end this process."
"We will not rush and we will not be rushed" in reaching an agreement, Kerry said to reporters in Vienna.
He indicated "real progress" is being made toward a comprehensive deal, adding the quality of the deal is the main concern.
"If in the end we are able to reach an agreement, it has to be one that will withstand the test of time. ... That's our goal here," Kerry said.
WATCH: Mary Alice Salinas reports from Vienna
White House comments
The White House echoed Kerry's comments, saying President Barack Obama would bring back from Vienna the U.S. negotiating team if talks do not appear to be constructive, spokesman Josh Earnest said.
"The fact that we've been very clear about our expectations for a final agreement makes it unlikely that the talks will drag on for many more weeks," Earnest said.
Iranian Foreign Minister Mohammad Javad Zarif said he was prepared to stay at the negotiating table in Vienna "as long as necessary" to clinch a deal with world powers on Tehran's contested nuclear program.
Earlier, Kerry held discussions with several of his counterparts, including Russian Foreign Minister Sergei Lavrov, by phone, about the ongoing negotiations.
Lavrov had told reporters in Ufa, Russia, where he is attending an economic summit, that Moscow favors Iran's push to lift a U.N. arms embargo.
"We are advocating for lifting of the arms embargo as soon as possible," he said.
But a U.S. official close to the talks told VOA, “No one is talking about lifting the arms embargo until years and years from now – if ever.”
Western officials have said they oppose ending the embargo, arguing the parameters of a framework adopted in Lausanne, Switzerland, in April call for important restrictions on conventional arms and ballistic missiles to be included in a new U.N. resolution to be drafted as part of a final agreement.
Lavrov said he planned to return to Vienna from Russia, where he and Chinese Foreign Minister Wang Yi traveled to attend the summit of so-called BRICS nations (Brazil, Russia, India, China and South Africa).
Negotiators have given themselves until Friday to reach a deal. But if a deal is not reached by 6 a.m. in Vienna (0400 GMT), the Republican-led U.S. Congress will have 60 days rather than 30 days to review it, extra time the Obama administration worries could create new chances to derail it.
Republican Senator Bob Corker, chairman of the U.S. Senate Foreign Relations Committee, said Thursday he did not see the continuation of Iran nuclear talks as a problem for U.S. lawmakers.
"I'm very happy that we're not rushing to a place and taking shortcuts on the remaining issues that are left. That is to me a very good thing," Corker told reporters shortly after Kerry's announcement.
Regarding a possible deal, U.S. Senator Chris Murphy, a Democrat, told VOA Thursday, “I am less optimistic than I was a week ago.
"It seems the Iranians are having a very hard time getting to ‘yes,’ but the administration has made it clear over and over that they are not going to accept a bad deal," Murphy said. "And if the president is ready to walk away from the table – if the Iranians don’t move on these last few remaining issues – I think that is comforting to his supporters and even his detractors here on Capitol Hill."
Republican Senator Ted Cruz, who is also a candidate in the 2016 presidential campaign, told VOA, "This Iranian nuclear deal goes from bad to worse to catastrophic.
"At this point, the Obama administration seems simply to be pursuing domestic political objectives and dramatically undermining the national security of this country. This deal only accelerates Iran acquiring nuclear weapons," Cruz added.
Western countries accuse Iran of seeking the capability to build nuclear weapons, while Iran has long insisted its nuclear program is solely for civilian purposes, such as medical research and generating power.
Heather Murdock and Brian Allen contributed to this report from Vienna. Michael Bowman contributed to this report from Capitol Hill. Some material came from Reuters.