The White House rejected the notion of putting timelines on its engagement with Iran Wednesday and indicated that its efforts could take a significant amount of time. While not opposing talks with Iran, Israel has been concerned that the Islamic republic would use the opportunity of negotiations to run out the clock on its nuclear program, and would like to see a time limit set to prevent such a scenario as well as to ratchet up pressure for Iranian compliance. But White House National Security Council spokesman Mike Hammer told foreign journalists Wednesday that "it's not appropriate at this time to be trying to establish timetables, but rather seeing how the engagement can move forward." He said the US was not looking for "talk for the sake of talk," but that "there are opportunities there for us to engage with the Iranian government." So far, he acknowledged that Iranian reactions to US overtures had been "mixed," as Iranian leaders had at times welcomed US President Barack Obama's efforts to appeal to the Iranian government, and at others put down such moves. But he took that as an indication that engagement, which he defended as "worthwhile," could be slow going. "We are in a process that we expect will take some time," he said. "We've had a difficult - at best - relationship in the past with Iran, and we're looking to see what is possible. But we're under no illusions that there will be any change in the near term." How the US and Israel each approach Iran is expected to be a major subject of conversations between Obama and Prime Minister Binyamin Netanyahu during their first meeting in Washington in mid-May. It has also come up in conversations that top US officials have had with moderate Arab leaders, who have also expressed concern behind closed doors over the Iranian nuclear program and how the pace of US talks could give Teheran too much latitude. Obama hosted King Abdullah of Jordan last week, in his first visit from a Middle East leader. Egyptian President Hosni Mubarak and Palestinian Authority President Mahmoud Abbas are expected as well in the coming month. Hammer said Wednesday that the Obama administration wanted to hear more from these key players about "what is possible" in moving the Arab-Israeli peace process forward before fleshing out the steps Obama would like each side to take - steps to which he alluded during Abdullah's visit. Abdullah asked that Obama not only prod both Israelis and Palestinians toward a two-state solution, but also that the president himself present a proposal for resolving the issues confronting the parties. "The initiative, in a sense, is what already is happening," Hammer said when asked about the White House presenting its own plan, referring to the frequent visits of high-level envoy George Mitchell and US Secretary of State Hillary Clinton to the region. "We have a president who is putting a high premium [on] seeing if we can make progress in the Middle East."