ANKARA (Reuters) – President Barack Obama will seek on Monday to shore up ties with Turkey, a Muslim country with growing clout whose help Washington needs to solve confrontations and conflicts from Iran to Afghanistan.

Obama's April 5-7 visit is a nod to Turkey's regional reach, economic power, unrivalled diplomatic contacts and status as a secular Muslim democracy that has accommodated political Islam.

It is last leg of an eight-day trip marking his debut as president on the world stage.

"The president will discuss the need for the U.S.-Turkish partnership to address regional challenges like the threat from terrorism, the war in Afghanistan, relations with Iran, and the shared goal of lasting peace between Israel and its neighbors," the White House said.

The U.S.-Turkish relationship suffered in 2003 when Ankara opposed the invasion of Iraq and refused to let U.S. troops deploy on its territory. Turkey has also criticized Washington for allowing Kurdish separatists to be based in northern Iraq from where they stage deadly attacks into Turkish territory.

Turkey is a major transit route for U.S. troops and equipment destined for Iraq as well as Afghanistan. As the United States reduces its troops there, Incirlik air force base could play a key role and Obama will discuss this.

"Obama wants to settle with Turkey over Iraq. It is a neighbor of Iraq and important to work with it as the United States moves troops out. Erdogan has hinted that he will allow the United States to use Turkey," said Hugh Pope, an analyst for International Crisis Group.

The United States also wants Turkey to be helpful in convincing its neighbors to allow their territory to become supply routes to Afghanistan where U.S. and other NATO forces are fighting a Taliban insurgency.

"Given Turkish activity and credibility in the wider region stretching from Afghanistan to the Middle East, passing over energy transit routes, Obama wants to give new blood to a real strategic partnership with Turkey," Cengiz Candar, a leading Turkish commentator and Middle East expert.

Polls show antipathy among most Turks for Washington.

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Obama has had an eye to ties with Turkey during his tour.

In Prague on Sunday, Obama urged the European Union to accept Turkey as a full member, in remarks rejected outright by France and met coolly by Germany.

And Turkey said it dropped objections to Anders Fogh Rasmussen becoming the next head of NATO after Obama guaranteed one of the Dane's deputies would be a Turk.

Obama may unlock the kind of goodwill generated by former U.S. President Bill Clinton when he came to Turkey in 1999, but risks dissipating it all if he uses the word "genocide" to describe the fate of Armenians in the Ottoman Empire in 1915.

In his election campaign, Obama pledged to call the massacres of Armenians genocide, and a resolution to so designate them was introduced in the U.S. House of Representatives last month.

Turkey accepts that many Christian Armenians were killed by Ottoman Turks during World War One, but denies that up to 1.5 million died as a result of systematic genocide.

"We're not out to ask favors from Obama. His presence is enough for us," a senior Turkish government official, who declined to be named, told Reuters. "His visit will give credibility to Turkey on the global stage and what we are trying to achieve in bringing peace to the region."

Turkey has sought to engage Syria with the West and acted as an indirect peace negotiator between Syria and Israel. It has also pushed to end the isolation of the Hamas militant group in Gaza and bring Iran out of isolation.

Turkey will not be the venue for Obama's promised major speech in a Muslim capital, but his stop will still be a way to emphasize his message of reaching out to Muslims.

Obama will give an address at the parliament in Ankara, and during a visit to Istanbul he will attend a reception of the United Nations Alliance of Civilizations, co-hosted by Turkey and Spain to bridge the gap between Western and Islamic countries. He will also meet students at an Islamic museum.

(Writing by Paul de Bendern; Editing by Alison Williams)