US sees enough progress at Iran talks to merit staying another day

"There are several difficult issues still remaining," US State Department spokeswoman says.

Kerry (2nd L) and French FM Fabius (2nd R) wait for a meeting in Lausanne  March 28, 2015. (photo credit: REUTERS)
Kerry (2nd L) and French FM Fabius (2nd R) wait for a meeting in Lausanne March 28, 2015.
(photo credit: REUTERS)
LAUSANNE, Switzerland - The United States believes there has been sufficient progress in negotiations between Iran and six world powers to warrant remaining in Switzerland past a midnight deadline, although tough questions remain, the State Department said on Tuesday.
"We've made enough progress in the last days to merit staying until Wednesday," acting spokeswoman Marie Harf said in a statement. "There are several difficult issues still remaining." 
No deal was announced on Tuesday, a self-proclaimed deadline, as the world's top diplomats worked through the day. The seven delegations have been in Switzerland for nearly a week attempting to hammer out an agreement that bridges all political disagreements on Iran's future nuclear work.
The five permanent members of the United Nations Security Council and Germany have sought to cap, restrict, monitor and partially roll back Iran's nuclear program for a finite period.
Deadline for a comprehensive nuclear accord— a formal, written agreement signed by each member state— is June 30.