Palestinian President Mahmoud Abbas, whose original four-year term expires on Friday, faces a legitimacy challenge that Israel's Gaza war has only postponed.

How it plays out will affect Abbas's ability to pursue peace talks with Israel. These have so far proved fruitless, earning him only derision from Hamas, which preaches armed resistance.

The Israeli onslaught on the Hamas-controlled Gaza Strip has temporarily eclipsed the dispute between Abbas's secular Fatah faction and its Islamist rivals over whether he must quit now.

"Currently we have a bigger problem than Jan. 9," Gaza-based Hamas spokesman Fawzi Barhoum said. "Our priority is to fight this war imposed on us and to defend our people."

For his part, Abbas, who contends that legal changes mean his term ends in 2010, has deferred plans to set a date for parliamentary and presidential elections, which he hoped would pre-empt any Hamas effort to depose or replace him.

A senior Palestinian official in Ramallah said Abbas was now preoccupied with ending the Gaza war. Once a ceasefire was in place, he would ask Hamas to renew reconciliation talks.

But with Palestinian emotions raw, the conflict over the presidency has not gone away -- and may get more personal.

"Hamas officials are pointing their fingers at Abbas as if he was the one who decided to launch the war on Gaza," said Ihad Zahdeh, a 32-year-old actor in the West Bank city of Hebron.

"It's hard for Abbas to gain support because he can't do anything for his people in Gaza and can't stop the aggression. Is this what he achieved from peace negotiations with Israel?"

Mustafa Barghouti, an independent former presidential candidate, said Palestinians saw the Gaza war as one aimed at all of them, not just Hamas. Israel would thus wind up weakening the Palestinian Authority, rather than its Islamist foes.

"What happened in Gaza has exposed the struggle between factions for an Authority that doesn't really exist because it is under occupation," he told Reuters. "It deepened the feeling that we are all under occupation and must unify against it."

But Palestinian unity has proved elusive in recent years.

A governance crisis erupted after Hamas won a January 2006 election and widened when the group drove Fatah forces from Gaza 18 months later, leaving Abbas's Palestinian Authority in partial control only of the Israeli-occupied West Bank.

"SENSE OF FEAR"

Abbas's revamped security forces, already repressing Hamas activity in the West Bank, have acted to limit solidarity rallies with Gaza in case these turn into anti-Abbas protests.

"There is a sense of fear in the West Bank. People are lying low," said International Crisis Group analyst Nicholas Pelham.

"The psychological impact of the Gaza campaign is going to be major in the West Bank, but at the moment it is being held in check by security measures. The pressure is mounting."

Hamas has also taken tough measures against remaining Fatah supporters in the Gaza Strip, even as Israeli bombs fall. It is trying to combat Israel's military might in a lopsided struggle, hoping its defiance will enhance its political prestige.

Bassem Ezbidi, a West Bank political analyst, said if Hamas emerged stronger, it would spell trouble for Abbas, who would be squeezed between the demands of Israel and the Islamists:

"And if Hamas loses, it might go underground ... But it will remain problematic for Abbas and try to ruin his project."

After Israel began its assault on Dec. 27, the Palestinian president echoed U.S. and Egyptian leaders in blaming Hamas for provoking it by scrapping a truce and firing rockets from Gaza.

That jarred with many Palestinians who argue that Israel had already shattered the six-month, Egyptian-mediated ceasefire with its punitive blockade of Gaza and raids on militants.

Abbas adjusted his tone and has since pressed hard for an immediate ceasefire, but the impression of indecision lingered.

"He has tried to look which way the wind is blowing and go with it," Pelham said. "There were advisers around him who saw benefits to be gained out of a humbling of Hamas in Gaza."

He said the viability of Abbas's statehood negotiations could depend on how the Gaza struggle turned out.

"You have to ask what is the scope for a peace process if the carnage continues in Gaza for many more days," he said.

"How achievable is this going to be in the aftermath of Gaza? If it is not, how will this affect Abbas's legitimacy?"

The outcome of Israel's election on Feb. 10, which will replace Prime Minister Ehud Olmert, and the attitude of the next U.S. administration under Barack Obama will also weigh heavily on the chances for reviving peace efforts.

"We don't know what Obama will do," Palestinian political analyst Ali Jarbawi said, adding that Abbas should avoid the same kind of talks that undercut his credibility last year. "If it is just to kiss Olmert on the cheeks, he should refuse."

It is hard to see how Abbas could "deliver" the Palestinians in any peace deal as long as the Hamas-Fatah rift persists.

"It was difficult and it will remain difficult," said Nasser Sharawi, 25, a student at al-Quds University in Hebron.

"Abbas wants peace and negotiation. Hamas wants fighting and liberation. They don't have a common goal."