When they met last summer in Ramallah, on the West Bank, Barack Obama promised Palestinian President Mahmoud Abbas he would be an active partner for peace, if he made it into the White House.

A year later, President Obama is sitting in the Oval Office, keeping his promise to tackle the Middle East conflict from the start of his term, but he is probably wondering whether Mr Abbas is the partner he was hoping for.

When the two men sit down for talks, Mr Obama will find the leader of a divided people, with limited legitimacy, with political authority over only part of the Palestinian territories and with a presidential term that some consider to have already expired in January.

With Hamas still in control of Gaza, many are wondering whether there is any point in starting peace talks with Mr Abbas if there are no guarantees he can bring all the Palestinians on board.

But Washington does not talk to Hamas (which it lists as a terrorist organisation) and if the Obama administration wants to start any process, Mr Abbas is the only Palestinian interlocutor available.

With some effort, it might start a dynamic that could have an impact on internal Palestinian politics.

Settlement freeze

Jordan's ambassador to the US, Prince Zeid Ra'ad al-Hussein, told the BBC that if there were tangible results from the peace efforts on key issues like settlements and East Jerusalem "then I think you will find much of the Arab and Islamic world swinging behind that effort".

But, he added, "we all need to see a peace treaty, we need to see a document and I think President Abbas would want to have a document so that he can show the Palestinian people there is an alternative narrative to the end game".

Middle East experts argue that this would also make it more difficult for Hamas to argue against peace negotiations.

So, hoping for a tangible success to bolster his position at home, Mr Abbas comes here with a few demands - he wants Israel to stop to all settlement activity and dismantle roadblocks in the West Bank.

And for the first time in years, he will find a US administration rather supportive of this long-standing Palestinian demand.

On Wednesday, after talks with her Egyptian counterpart, Ahmad Aboul Gheith, US Secretary of State Hillary Clinton told Israel it had to freeze all settlement activity without exception, in what was probably the most vocal and explicit such call in years from a US administration.

"The President was very clear when Prime Minister Netanyahu was here. He wants to see a stop to settlements - not some settlements, not outposts, not natural growth exceptions," she said.

"We think it is in the best interests of the effort that we are engaged in that settlement expansion cease. That is our position. That is what we have communicated very clearly, not only to the Israelis but to the Palestinians and others. And we intend to press that point."

Israel has already rejected that call and Mr Netanyahu has said that "natural growth" - construction within the boundaries of existing settlements - will continue.

It is a rare public disagreement between the two allies and a sharp contrast to the smooth sailing between the two countries during President George W Bush's eight years in office.

'57-state solution'

When Mr Netanyahu came to Washington last week, he resisted publicly endorsing the idea of a two-state solution with the Palestinians, which the Obama administration has called for.

And he had his own demands - security for his country and a recognition of Israel's right to exist.

Arab countries have promised that under the 2002 Arab peace initiative, Israel would get full, normal relations with all 22 Arab states.

King Abdullah of Jordan has even spoken for a "57-state solution" that would bring in all 57 members of the Organisation of Islamic Countries.

Israel wants its Arab neighbours to start demonstrating their willingness to engage with their long-time foe, with confidence-building measures like opening Israeli trade missions or allowing over-flights by Israel's national carrier, El Al.

The Jordanian ambassador in Washington said Arab states were discussing what steps they could take on the road to peace but reiterated that what was needed first was the start of final status negotiations with a clear end-goal and a specific time-frame.

Mr Netanyahu also came with another demand - he wants Iran's nuclear and regional ambitions reined in and made clear to President Obama the issue was his top priority.

And he emphasised the fact that some Sunni Arab countries are also worried about the ambitions of the Shia leadership in Tehran.

Time running out

It is an interesting area of overlapping concern, but a very tricky one to build on for Arab countries.

"The Arab [states] cannot survive a deal with Israel against Iran, if they don't deliver on the Palestinian issue," said Ziad Asali of the American Task Force for Palestine.

"[The backlash] would overwhelm them and they would not survive it," he added.

This is just another stark warning to be added to the one that has been repeated for some months now - time is running out for a peace agreement in the Middle East.

Some caution against talk of a war within 18 months if there is no peace deal for fear it will turn into a self-fulfilling prophecy.

But the warning may help focus the minds of those involved.

So what is at stake when Mr Obama and Mr Abbas sit down for talks is a regional, comprehensive peace not just a future Palestinian-Israeli agreement.

But that agreement remains the starting point and the Palestinian leader will have to show he can deliver on his end of that bargain.