"They have made genuine progress... but there continues to be some sticking points that remain unresolved," White House spokesman Josh Earnest told reporters in Washington on Monday.
He added that President BarackObama"has directed his team to remain engaged and participate in conversations as long as those conversations remain useful."
The White House spokesman alsosuggested that the negotiations in Vienna could go into Tuesday.
Earlier, Iranian Foreign Minister Mohammad Javad Zarif said it is possible that the talks will come to a conclusion on Tuesday.
Zarif made the remarks from the balcony of Palais Coburg hotel, the venue for the negotiations, in response to a question asked by Press TV reporter Homa Lezgee, who is in Vienna to cover the talks.
The foreign minister also tweeted: "If#IranDealreached, triumph of diplomacy means we all will have won when we all could have lost. Plain and simple; no spin needed."
[caption id="" align="alignnone" width="550"]
German Foreign Minister Frank-Walter Steinmeier (L), French Foreign Minister Laurent Fabius (2nd L), Chinese Foreign Minister Wang Yi (3rd L), European Union foreign policy chief Federica Mogherini (Centre in red), US Secretary of State John Kerry (4th R) and Russian Foreign Minister Sergei Lavrov (R) meet at a hotel in Vienna on July 13, 2015. (AFP photo)[/caption]Iran and the P5+1 countries - the United States, Britain, France, Russia, China and Germany - have been engaged in crucial talks in the Austrian capital Vienna towards reaching a landmark agreement over Tehrans nuclear energy program.
The negotiating sides missed an initial deadline on June 30 and all parties agreed on a new July 7 deadline. Now it seems that negotiations will continue at least until Tuesday.
This round of negotiations in Vienna, which has capped two years of international talks, is seen as the last push to resolve the Wests 13-year nuclear standoff with Iran.
