Israeli Prime Minister Ariel Sharon is meeting US President George W Bush in Washington to discuss the American-backed Middle East peace plan known as the roadmap.
Sharon wants to focus on Palestinian disarmament
The talks at the White House, which follow a meeting four days ago between Mr Bush and the Palestinian Prime Minister Mahmoud Abbas, are expected to focus on concerns that a month-old ceasefire agreed by Palestinian militants is under threat.
Correspondents say Mr Bush is likely to put more pressure than usual on the Israeli prime minister to make concessions.
The Palestinians say an Israeli separation fence under construction in the West Bank and the continued growth of Jewish settlements are undermining President Bush's own vision of an independent Palestinian state.
The Israelis counter by saying that the Palestinian security forces are not using the lull in violence to prevent militant groups regrouping and rearming.
Mr Bush has criticised the construction of the security fence, but he is expected to support Mr Sharon's calls for active Palestinian steps to dismantle what the Israelis describe as terrorist organisations and their infrastructure.
ROADMAP MAIN POINTS
Phase 1 (to May 2003): End to Palestinian violence; Palestinian political reform; Israeli withdrawal and freeze on settlement expansion; Palestinian elections
Phase 2: (June-Dec 2003) Creation of an independent Palestinian state; international conference and international monitoring of compliance with roadmap
Phase 3 (2004-2005): Second international conference; permanent status agreement and end of conflict; agreement on final borders, Jerusalem, refugees and settlements; Arab states to agree to peace deals with Israel
Israel's decision to release 500 Palestinian prisoners is also likely to be on the agenda.
The visit by Mr Sharon, who met US national security adviser Condoleezza Rice on Monday, is being closely followed by both sides.
The BBC's Nick Thorpe says the importance of the US role in the peace process cannot be underestimated, and every word President Bush says in public will be carefully noted for clues as to where American pressure will be brought to bear.
Prisoner releases 'not enough'
The issue of the security barrier is important to Israelis living near the West Bank.
The mayor of Kfar Saba, a town a short way from the fence, says that, while it will not stop all attacks being launched from the West Bank, it will make a difference.
"If they would stop, absolutely, the terror activities here, there would be no need for the fence," he said. "But for the time being, we have to care for ourselves, nobody will do it for us, and these are means that we need for the time being."
Five protesters were wounded after Israeli police used tear gas and rubber bullets to break up more than 200 demonstrators at the fence near the West Bank town of Jenin on Monday.
For the Palestinians, another major issue is Israel's detention of thousands of prisoners.
Radie Jarai, Deputy Minister of Detainee Affairs for the Palestinian Authority, says Mr Sharon's concession to release 500 prisoners does not go far enough.
"We have about 6,000 Palestinians imprisoned in Israeli jails, and to release 400, or 500, is just starting," he said.
"In the last two weeks, there were more than 300 detention cases in the West Bank and Gaza Strip. So it is just trying to mislead the public opinion that Israel is making progress in the peace process."