(Bloomberg) — U.S. Secretary of State John Kerry said
“tricky issues” remain to be resolved if diplomats are to meet
their timetable and reach an outline agreement on Iran’s nuclear
program by the end of Tuesday.

“We are working late into the night and obviously into
tomorrow,” Kerry told CNN on Monday evening during a break in
talks in Lausanne, Switzerland. “There is a little more light
there today,” he said.

The effort to end a 12-year standoff with Iran enters
deadline day with negotiators still divided over the pace of
easing sanctions on Iran, and the limits to be imposed on its
research to ensure it can’t obtain nuclear weapons.

A framework accord by March 31 would be a first step toward
ending Iran’s economic isolation and allowing the country with
the world’s fourth-biggest oil reserves to export freely again.
An additional three months are envisaged for reaching a detailed
final agreement.

Talks are stuck on how to roll back the sanctions that have
slashed Iran’s oil output, and how to re-impose them should Iran
violate the agreement, a European diplomat who spoke on
condition of not being identified said on Monday. Both sides are
playing a high-stakes game of chicken and the situation was
changing hour-by-hour, the negotiator said.

Iran’s Supreme Leader Ayatollah Ali Khamenei has demanded
the immediate end of sanctions. Western powers have proposed
lifting United Nations sanctions over four to six years, while
other curbs may remain in place for as long as a decade,
according to two people involved in the talks.

‘Path Forward’

If no deal is reached on Tuesday, “we have to look at the
path forward,” U.S. State Department spokeswoman Marie Harf
said Monday. She said no decision has been made on how to
dispose of much of Iran’s enriched uranium, a key element in
ensuring that the nuclear program is peaceful.

The six powers negotiating with Iran would prefer that the
uranium, which is used to fabricate fuel for power plants and a
medical reactor, be transferred to a guarantor nation, though
other options are being discussed, the European diplomat said.

One indicator that a deal may be within reach on Tuesday
would be the return of Russian Foreign Minister Sergei Lavrov.
Lavrov left the talks on Monday for a Moscow meeting with the
foreign minister of the Pacific Island of Vanuatu. He would come
back only if there’s a “realistic” prospect of a deal, Russian
Foreign Ministry spokeswoman Maria Zakharova said.

Final Sprint

China’s Foreign Minister Wang Yi sounded an optimistic
note, saying that “the scale of disagreement has shrunk” as
diplomats enter what he likened to the final sprint of their
marathon.

A failure of the talks would be a blow to President Barack
Obama, who has backed two years of negotiations with Iran
despite domestic opposition. Republicans and many Democrats in
Congress say they agree with Israeli Prime Minister Benjamin
Netanyahu’s argument that the emerging accord is dangerous.

“In Lausanne, they are closing their eyes,” Netanyahu’s
office said Monday. “But we are not closing our eyes and we
will continue to act against every threat.”

In Iran, hard-liners issued a last-ditch warning to Foreign
Minister Mohammad Javad Zarif, telling him not to make
concessions that cross the Islamic Republic’s red lines.

It’s unacceptable for a deal to keep UN sanctions in place,
or require Iran to make irrevocable commitments while the other
side’s steps could be reversed, said Hossein Shariatmadari,
editor-in-chief of the conservative Kayhan newspaper.

To contact the reporters on this story:
Indira A.R. Lakshmanan in Lausanne, Switzerland at

ilakshmanan@bloomberg.net;
Jonathan Tirone in Lausanne, Switzerland at
jtirone@bloomberg.net;
Ladane Nasseri in Lausanne, Switzerland at
lnasseri@bloomberg.net

To contact the editors responsible for this story:
John Walcott at
jwalcott9@bloomberg.net
Ben Holland, Larry Liebert