Senators in the US have said the Bush administration should hold direct talks with Iran on its nuclear programme.
Iran has refused to halt work on uranium enrichment
The calls for bilateral talks contrast with the president's multilateral approach through the UN.
Richard Lugar, the Republican chairman of the Senate foreign relations committee, also said it was too soon to press for sanctions.
The UN Security Council is due to meet later this month to discuss Iran, which says it has produced enriched uranium.
Iran made the announcement last week, despite being given 30 days by the council to halt all sensitive atomic activities.
US Secretary of State Condoleezza Rice has said the Security Council would have to look at options to compel Iran to "obey the international system".
Ms Rice said Iran might face punitive sanctions
But Sen Lugar said on Sunday it would be "useful" for the US to hold direct talks with Iran.
He said on US television: "The Iranians are a part of the energy picture. We need to talk about that."
Another senator, Christopher Dodd, agreed: "I happen to believe you need direct talks. It doesn't mean you agree with them.... But there's an option."
However, Republican House representative Duncan Hunter said that in order to have talks with Iran, "you need to have a receptive audience".
The US recently agreed to direct talks - but only on the issue of the instability in Iraq.
The Security Council is due to meet on 28 April - the deadline it gave Iran.
Tehran has insisted it will continue its nuclear programme as it is purely for peaceful, energy purposes.
Western nations suspect Iran of wanting to develop a nuclear weapon. Tehran says it has succeeded in enriching uranium, but insists its programme is purely peaceful.
Ms Rice said last week: "There will have to be some consequence for that action and that defiance. We will look at a whole range of options available to the Security Council."
She said the council would have to look at a Chapter 7 resolution - which UN members are mandated to comply with.
However, Russia and China, which hold council vetoes, oppose sanctions.