UNITED NATIONS - (AP) - Exhorting world leaders to push past yearsof cynicism and pessimism, President Barack Obama challenged thecountries of the United Nations on Thursday to unite around peaceefforts that he said could achieve agreement within a year tocreate an independent Palestine and a secure Israel.

Obama, in a speech to the U.N. General Assembly, urged fellowworld leaders to press forward with renewed determination in thequest for Mideast peace, an effort that he acknowledged hasencountered "few peaks and many valleys." Without an agreement, he said, "more blood will be shed" and"this Holy Land will remain a symbol of our differences, insteadof our common humanity."

As Obama spoke, Israel's seat in the hall sat empty because itwas a Jewish holiday. Palestinian President Mahmoud Abbas waspresent, listening to the president through a translator'searphone. Obama's call for a Palestinian state drew a burst ofapplause from throughout the hall.

Obama's one-year timeline is ambitious even if the Mideast peaceprocess faced the best of circumstances, which it does not. He madeno mention of the militant Hamas movement, which controls the GazaStrip and refuses to accept Israel's right to exist.

The failure of past peace efforts has left both sides with rigiddemands and public ambivalence about the value of a negotiatedsettlement.

Obama spoke with resolve of the need to address trouble spotsaround the world, but he tended first to the economic concerns thatabound both at home and abroad.

"There is much to show for our efforts," he said, recallingthe economic turmoil of years past. "We cannot - and will not -rest until these seeds of progress grow into a broader prosperityfor all Americans and for people around globe."

On a pressing security issue, Obama defended hisadministration's approach to engaging Iran in negotiations over itsnuclear program - an effort that has failed thus far. In July theadministration imposed a new set of sanctions on Iran.

"The door remains open to diplomacy should Iran choose to walkthrough it," he said. "But the Iranian government mustdemonstrate a clear and credible commitment and confirm to theworld the peaceful intent of its nuclear program."

Iran recently has indicated interest in restarting talks withthe West, and on Wednesday the five permanent members of the U.N.Security Council and Germany offered Iran another chance to enternegotiations.

Obama also spoke to the promotion of human rights, opengovernment and democracy - familiar themes from a president who haspushed for international cooperation against repression andtyranny.

"Make no mistake: The ultimate success of democracy in theworld won't come because the United States dictates it. It willcome because individual citizens demand a say in how they aregoverned," he said. "There is no soil where this cannot takeroot."

Obama drew applause in mentioning U.N. efforts to protect therights of women, and he urged all nations to act againstoppression.

"Do no stand idly by, don't be silent when dissidentseverywhere are imprisoned and protesters are beaten," he said.

The president devoted his greatest attention to theIsraeli-Palestinian conflict, underscoring the urgency ofovercoming the hurdles that he has met less than a month afterrelaunching direct negotiations between the parties.

Abbas is threatening to walk out of the talks if Israel does notextend a slowdown on construction of Jewish settlements in the WestBank that is set to expire next week. Israeli Prime MinisterBenjamin Netanyahu has said he will not extend that partial freeze.

The looming expiration appears to have stalled the negotiations,which got under way in early September in Washington between Abbasand Netanyahu and then moved to a second round in Egypt and inJerusalem last week. That second round ended inconclusively withlittle visible progress and without the expected announcement of athird session.

Obama underscored the administration's position that thesettlement moratorium should be extended, saying it "has made adifference on the ground, and improved the atmosphere for talks."

Secretary of State Hillary Rodham Clinton and theadministration's special Middle East peace envoy George Mitchellhave been meeting with officials from both sides and otherinterested parties this week in New York but seem to have madelittle headway.

Faced with the real possibility of the collapse of negotiations,Obama implored the international community to get behind the ideaof peace and forget favoritism to one side or the other.

"Those of us who are friends of Israel must understand thattrue security for the Jewish state requires an independentPalestine," he said. "And those of us who are friends of thePalestinians must understand that the rights of the Palestinianpeople will be won only through peaceful means - including genuinereconciliation with a secure Israel."

Obama urged the U.N. in its 60th year to look beyond past MiddleEast peace failures and get on with the task at hand.

"We can come back here, next year, as we have for the last 60,and make long speeches about it," he said. "We can read familiarlists of grievances. We can table the same resolutions. We canfurther empower the forces of rejectionism and hate."

"Or we can say that this time will be different, that this timewe will not let terror or turbulence or posturing or petty politicsstand in the way."

Obama's speech came amid a three-day U.N.-dominated trip to NewYork, where the president was also to meet privately with theleaders of China, Japan, Colombia, Azerbaijan and Kyrgyzstan. Inaddition, he was to host Southeast Asian leaders and attend ameeting aimed at preventing renewed civil war in Sudan.