The incoming Obama administration is prepared to abandon George Bush's ­doctrine of isolating Hamas by establishing a channel to the Islamist organisation, sources close to the transition team say.

The move to open contacts with Hamas, which could be initiated through the US intelligence services, would represent a definitive break with the Bush ­presidency's ostracising of the group. The state department has designated Hamas a terrorist organisation, and in 2006 ­Congress passed a law banning US financial aid to the group.

The Guardian has spoken to three ­people with knowledge of the discussions in the Obama camp. There is no talk of Obama approving direct diplomatic negotiations with Hamas early on, but he is being urged by advisers to initiate low-level or clandestine approaches, and there is growing recognition in Washington that the policy of ostracising Hamas is counter-productive. A tested course would be to start ­contacts through Hamas and the US intelligence services, similar to the secret process through which the US engaged with the PLO in the 1970s. Israel did not become aware of the contacts until much later.

A UN resolution was agreed last night at the UN, calling for an immediate and unconditional ceasefire between Hamas and Israeli forces in Gaza. The resolution was passed, though the US, represented by secretary of state Condoleezza Rice, abstained.

Richard Haass, a diplomat under both Bush presidents who was named by a number of news organisations this week as Obama's choice for Middle East envoy, supports low-level contacts with Hamas provided there is a ceasefire in place and a Hamas-Fatah reconciliation emerges.

Another potential contender for a ­foreign policy role in the Obama administration suggested that the president-elect would not be bound by the Bush doctrine of isolating Hamas.

"This is going to be an administration that is committed to negotiating with ­critical parties on critical issues," the source said.

There are a number of options that would avoid a politically toxic scenario for Obama of seeming to give legitimacy to Hamas.

"Secret envoys, multilateral six-party talk-like approaches. The total isolation of Hamas that we promulgated under Bush is going to end," said Steve Clemons, the director of the American Strategy ­Programme at the New America ­Foundation. "You could do something through the Europeans. You could invent a structure that is multilateral. It is going to be hard for the neocons to swallow," he said. "I think it is going to happen."

But one Middle East expert close to the transition team said: "It is highly unlikely that they will be public about it."

The two weeks since Israel began its military campaign against Gaza have heightened anticipation about how Obama intends to deal with the Middle East. He adopted a strongly pro-Israel position during the election campaign, as did his erstwhile opponent and choice for secretary of state, Hillary Clinton. But it is widely thought Obama would adopt a more even-handed approach once he is president.

His main priority now, in the remaining days before his inauguration, is to ensure the crisis does not rob him of the chance to set his own foreign policy agenda, rather than merely react to events.

"We will be perceived to be weak and feckless if we are perceived to be on the margins, unable to persuade the Israelis, unable to work with the international community to end this," said Aaron David Miller, a former state department adviser on the Middle East.

"Unless he is prepared to adopt a policy that is tougher, fairer and smarter than both of his predecessors you might as well hang a closed-for-the-season sign on any chance of America playing an effective role in defusing the current crisis or the broader crisis," he said.

Obama has defined himself in part by his willingness to talk to America's enemies. But the president-elect would be wary of being seen to give legitimacy to Hamas as a consequence of the war in Gaza.

Bruce Hoffman, a ­counterterrorism expert at George­town University's school of foreign ­service, said it was unlikely that Obama would move to initiate contacts with Hamas unless the radical faction in Damascus was crippled by the conflict in Gaza. "This would really be dependent on Hamas's military wing having suffered a real, almost decisive, drubbing."

Even with such caveats, there is ­growing agreement, among Republicans as well as Democrats, on the need to engage Hamas to achieve a sustainable peace in the Middle East – even among Obama's close advisers. In an article published on Wednesday on the website Foreign Affairs, but apparently written before the fighting in Gaza, Haass, who is president of the Council on Foreign Relations, wrote: "If the ceasefire between Israel and Hamas continues to hold and a Hamas-PA reconciliation emerges, the Obama administration should deal with the joint Palestinian leadership and authorise low-level contact between US officials and Hamas in Gaza." The article was written with Martin Indyk, a former US ambassador to Israel and an adviser to Hillary Clinton.

Obama has said repeatedly that ­restoring America's image in the world would rank among the top priorities of his administration, and there has been widespread praise for his choice of Clinton as secretary of state and Jim Jones, the former Marine Corps commandant, as his national security adviser.

He is expected to demonstrate that commitment to charting a new foreign policy within days when he is expected to name a roster of envoys to take charge of key foreign policy areas: Iran, the Israeli-Palestinian conflict, India-Pakistan, and North Korea.

Obama has frustrated and confused those who had been looking for a more evenhanded approach to the Israeli-­Palestinian conflict by his refusal to make any substantive comment on Israel's ­military campaign on Gaza, nearly two weeks on.

He said on Wednesday: "We cannot be sending a message to the world that there are two different administrations conducting foreign policy.

"Until I take office, it would be ­imprudent of me to start sending out ­signals that somehow we are running ­foreign policy when I am not legally authorised to do so."