The United States might extend a deadline to reach a comprehensive agreement on Iran 's nuclear program , a senior State Department official told CNN . International negotiators in Vienna , Austria , are scrambling to reach a deal by Monday 's deadline . `` It is only natural that less than 48 hours from the deadline we are discussing a range of options , '' the official said . `` An extension is one of those options . '' Both sides appeared to be pointing to the possibility of yet another extension to the monthslong series of negotiations , whose final outcome is expected to have a lasting effect on Iran 's relations with the West . U.S. President Barack Obama , asked about the deadline in an interview broadcast Sunday morning on ABC 's `` This Week , '' did n't reject the idea . `` I think that what we 're going to do is take a look at what emerges over the course of the weekend , '' he said . When asked if Congress would approve any agreement with Iran , Obama said , `` I 'm confident that if we reach a deal that is verifiable and assures that Iran does not have breakout capacity , that not only can I persuade Congress , but I can persuade the American people that it 's the right thing to do . '' But media in Tehran were skeptical about the deadline . Based on the differences that remain between negotiators , and in light of the limited time remaining , reaching a deal by Monday `` would be impossible , '' the Iranian Students ' News Agency reported Sunday , citing an unidentified Iranian official involved in the talks . 'Big gaps ' U.S. Secretary of State John Kerry , who is in Vienna for the talks , said Saturday that `` big gaps '' remained between negotiators . A senior U.S. State Department official on Sunday referred back to those comments but told CNN that `` we are discussing the broad range of issues and we are continuing to take steps forward . '' But the progress being made is only `` chipping away '' at the issues , the official cautioned . `` The focus of discussions remains on an agreement , but we are discussing both internally and with our partners a range of options for the best path forward , '' the official said . The negotiations are between Iran and the group known as the P5+1 , consisting of Germany , the United States , Russia , China , France and Britain . Russian Foreign Minister Sergey Lavrov will arrive in Vienna on Sunday evening to participate in the talks , Russia 's state-run TASS news agency reported , citing a source in the Russian delegation . A deal could bring about an end to significant sanctions against Tehran and a warming of relations with the West . The absence of a deal would most likely ramp up tensions and could lead to more punitive measures -- and even confrontation -- over Iran 's controversial nuclear program . Will Congress kill an Iran nuclear deal ? Pressure on both sides . Iran insists that like other countries , it has a right to develop nuclear power for peaceful purposes . But Western powers have accused it of trying to develop not just nuclear energy but nuclear weapons as well . The head of the International Atomic Energy Agency , who is not part of the Vienna talks , said Thursday that Iranian authorities are continuing to deny his agency access to a sensitive military complex suspected of being a site of nuclear activities . Obama and Iranian President Hassan Rouhani face domestic political pressure to strike a deal . An extension could sharpen opposition both in the U.S. and in Iran . Republicans take control of the U.S. Senate in January and lawmakers have threatened fresh sanctions on Iran if a deal is not reached . Although Obama has the power to veto , just the prospect of additional sanctions could drive Iran away from the table . Rouhani and Foreign Minister Javad Zarif , the lead Iranian negotiator , are under fire from conservatives and lawmakers who were skeptical of the interim deal and have said a final agreement must be ratified by parliament . Earlier this month 200 Iranian members of parliament signed a statement demanding that Iranian negotiators `` vigorously defend '' the country 's nuclear rights and ensure a `` total lifting of sanctions . '' The senior U.S. State Department official told CNN on Sunday that the Iranians `` still have big decisions that need to be made . '' International nuclear watchdog : Iran needs to cooperate .
State Department official says extending deadline is an option . Russian foreign minister is heading to Austria for the talks , state media report . Comment: Both sides appear to leave open the possibility of a further extension beyond Monday .