Ahmed Yousef, Palestinian intellectual, diplomat, and self-described public-relations extraordinaire, champions many causes.

Bridging the chasm that divides Iran's Shiite theocracy from the Muslim world's majority Sunnis is one. Reconciling Islamist governance with democracy and human rights is another.

But perhaps his biggest challenge is putting a more moderate face on Hamas, the Islamist group that rules Gaza and is more noteworthy in some circles for its cosy relations with Iran's Islamic republic and the suicide bombings it carried out in Israel's cafes and buses. For Mr Yousef, the deputy foreign minister for the Hamas government in Gaza, that would seem an all but impossible task.

The 59-year-old, American-educated Mr Yousef merely shrugs and keeps on moving.

"Believe me, many times, the things I say set the agenda," he said on his way to the Rafah border crossing, where he planned to meet an aid convoy attempting to break Israel's blockade.

If Hamas had a face to project to the outside world, it would probably be the slightly bearded, somewhat grizzled one of Mr Yousef.

He speaks better English than many of his colleagues, honed from spending nearly two decades in the United States. He describes his ideal vision of Hamas rule with words such as "moderate", "human rights" and "democracy".

From his seaside office in the foreign ministry building in Gaza City, he walks the hallways in slippers and what resembles pyjamas, exuding a relaxed demeanour.

That may be why, whenever crisis strikes Gaza, his is the face representing Hamas on television sets from Europe to Japan. He gave 60 media interviews in one day following the Israeli raid on a Turkish flotilla sent to break the siege on Gaza in May, a feat that he says may get him recognition from the Guinness Book of World Records.

"I was completely sunburned, I lost my voice after that day," said Mr Yousef, who, in addition to Arabic and English, speaks Turkish, French and Hebrew.

And yet, his dovish positions have also marginalised him from what observers call Hamas's more hawkish inner circle. And for all his media appearances, it is not entirely clear to what extent Mr Yousef actually speaks for the Islamist government, or whether his calls for moderation are merely driven by shrewd political calculation.

This was evident in his most recent attempts to influence Hamas ideology, which has caused officials in the group to roll their eyes. In two recent pamphlets, he argues for Hamas to reform along the lines of the Islamist-democratic model of Turkey's ruling Justice and Development Party. In another, he argues that the religious-political ideology of the Sunni Muslim Brotherhood, from which Hamas originated, is not incompatible with Shiite Iran's theocratic government.

"These are just his own ideas, they are not policy," said a dismissive Taher Nou Nou, who calls himself an "official" Hamas government spokesman.

Some Israeli commentators, on the other hand, see Mr Yousef's writings as a not-so-veiled attempt to deepen strategic relations, under the cover of religious rapprochement, between the anti-Western-Israeli axis of Hamas and Tehran.

"Yousef, in fact, attempts to rewrite the history of Hamas-Iran relations over the last six decades so that partnership becomes a duty for true believers," Ehud Yaari, an Israel-based analyst for the Washington Institute for Near East Policy, a US research organisation, wrote in November.

One thing for sure, though, is that Hamas's leadership has not rewarded Mr Yousef's calls for moderation.

His criticism of suicide bombs during the second intifada and his so-called "soft" conditions for a ceasefire with Israel led to his demotion from a short-lived stint as political adviser to Ismail Haniyeh, the Hamas prime minister. The person whom Gazans once referred to as "the man who has Haniyeh's ear" was shunted aside following Hamas's takeover of Gaza in 2007, to a secluded office in Gaza's foreign ministry building.

Analysts in Gaza, speaking on condition of anonymity, said he has also fallen out with Khaled Mashaal, Hamas's Damascus-based leader, for similar reasons. It is, they said, another example of the group's internal divisions, and how those on the side of the hardliners have steadily grabbed the reins of influence from doves.

Mr Yousef acknowledges this trend, but defends his positions as necessary when facing what he calls efforts by the United States and certain Arab countries to divide Sunnis from Shiites.

Yet, he criticises the hardened stances of some Hamas colleagues, calling them victims of Gaza's "siege mentality".

"Those people, when they grow up seeing funerals every day, the Israeli incursions and aggression, when you see all the bloody things every day and night, I'm sure this hardens your position," he said. "I was lucky enough to live in the United States, where you learn to consider dialogue, to listen to each other."

Though born in a Palestinian refugee camp in Gaza, Mr Yousef is considered somewhat of an outsider in Hamas. For most of the group's formative years, he was abroad. He formally joined Hamas in 2006, when it won the Palestinian Legislative Council elections.

On a scholarship offered by the United Arab Emirates, he moved to the US in 1982, studying at Colorado State University and then earning a PhD in political science at the University of Missouri-Columbia.

Like many of his generation, he turned to political Islam after the shock of Israel's victory during the Arab-Israeli war. Aged 17 at the time, he said, he became drawn to the writings of Sayyid Qutb, an Egyptian intellectual who, after studying in the US, went on to lay the ideological groundwork for al Qa'eda.

But unlike Qutb, who despised what he saw as America's moral depravity, Mr Yousef describes his experiences in America as enlightening, even if the country now considers his employer a terrorist group.

"I had this kind of belief that Jews and Christians were working against Muslims and against Islam until I went there. Then I saw, no, that this was 100 per cent false," he said.

Learning to discuss issues with Jews and Christians, rather than by the confrontational approach that has come to define Hamas, taught him not to "depend on, how do you call it, the concept of taking the law into your hands.

"You learned to depend on your mind, not your might," he said.

He still likes to consider himself one of the beltway intellectuals and policy-wonks of Washington, DC. From the nearby suburb of Springfield, Virginia, he managed an Islamic think tank, the United Association for Study and Research.

One of his most distinct memories is a visit in 1998 to the White House, where he met Hillary Clinton, then the first lady to her president-husband, Bill Clinton.

His connections with America persist to this day. Some of his family still live there, and three of his eight children hold US passports.

But his days of cavorting with Washington intellectuals and diplomats are a distant memory. He has been unable to leave Gaza for two years, the result of Israel's blockade and Egypt's willingness to help enforce it.

Nowadays, Gaza's most well-known diplomat likes to ponder the future of Hamas and his place in the group from his high-rise office building.

Admiring the view of the Mediterranean that stretches over the horizon and eventually to Europe on a recent afternoon, he remarked about the unusually calm water, as if to highlight both his and Gaza's isolation.

"Usually, from up here you can see the Israeli gunboats in the water," he said.