Mahmoud Abbas, tipped to become the new Palestinian president, says he will not fight against militant groups.
Palestinians chanted their support for Mahmoud Abbas in Rafah
After receiving a hero's welcome by militants in the Gaza Strip, Mr Abbas said he would use persuasion to bring about a ceasefire with Israel.
At one point during the visit at Rafah refugee camp he was hoisted on the shoulders of gunmen clad in black.
The Palestinian election, on 9 January, will decide who will take over from Yasser Arafat who died in November.
Mr Abbas is often said to be less charismatic and to have less popular support than Arafat, but he was loudly cheered by the crowd.
On the 40th anniversary of his Fatah faction, Mr Abbas repeated his call for an independent Palestinian state in the West Bank, Gaza Strip and east Jerusalem.
He has the tacit support of Israel and the US as a potential partner in a revived peace process.
Israeli Prime Minister Ariel Sharon refused to negotiate with Arafat, accusing him of backing terrorism.
Escape through window
Mr Abbas, also known as Abu Mazen, has been campaigning hard in Gaza - a stronghold of organisations like Hamas and Islamic Jihad.
The two groups are committed to armed confrontation with Israel.
In Rafah, where scores of Palestinians have been killed in the four-year uprising, Mr Abbas praised the residents, those killed in fighting with Israel, and the militants on the run.
In an interview with the BBC, Mr Abbas said he believed that he might be able to persuade the militants to agree a ceasefire, if elected.
"We will not use force with Hamas but we will use the way of persuasion and negotiation," he said.
"We consider that fighting among Palestinians is a red line that must not be crossed."
The Associated Press news agency said the presidential front-runner had gone even further and vowed to protect the militants from Israeli attacks.
"When we see them, when we meet them, and when they welcome us, we owe them," AP quoted him as saying.
"This debt always is to protect them from assassination, to protect them from killing, and all these things they are subject to by the Israelis."
The hall where Mr Abbas spoke became so crowded that he had to clamber through a window to get out.