WASHINGTON (Reuters) — US President George W. Bush is likely to encourage politicians in Baghdad to form a moderate coalition when he revamps his Iraq strategy next month but analysts are sceptical it will tame sectarian warfare.Bush held meetings this month with Shi'ite, Sunni and Kurdish leaders from Iraq. He hopes that a governing bloc of moderates will allow for the marginalisation of militants like the cleric Moqtada al-Sadr, whose Mehdi Army is viewed by the Pentagon as one of the biggest threats to security in Iraq.

"I can see why the administration would want a stronger government coalition," said Daniel Serwer, a scholar at the US Institutes of Peace. "It may not work because the situation on the ground is so difficult."

Serwer, who advised the high-level Iraq Study Group that devised recommendations for changing course in Iraq, added: "It's always a high-wire act to try to shift a government coalition."

Bush, at his year-end news conference on Wednesday, acknowledged sectarian violence had stymied US efforts to bring security and stability to Iraq. The rampant bloodshed has led to rising calls at home for a pullout of US troops.

Instead the president underscored his determination to press ahead in Iraq and is weighing a short-term boost in the US troop presence.

"It's becoming very apparent to the people of Iraq that there are extremists and radicals who are anxious to stop the advance of a free society," Bush said.

"And therefore, a moderate coalition signals to the vast majority of the people of Iraq that we have a unity government," Bush said, adding that would "marginalise those who use violence to achieve political objectives".

The administration's focus on seeking a moderate coalition suggests that Bush probably has rejected another approach said to be under review — the so-called "80 percent" proposal that would throw US support behind Iraq's majority Shi'ites and the Kurds while largely abandoning the Sunnis.

Shi'ites, oppressed under Saddam Hussein, form the largest bloc in Iraq's parliament. But the Bush administration has long been frustrated by Iraqi Prime Minister Nuri al-Maliki's political reliance on loyalists to Sadr.

Bush has met with Iraqi Vice President Tariq al-Hashemi, a Sunni, and Abdul Aziz al-Hakim, leader of the powerful Shi'ite Supreme Council for the Islamic Revolution in Iraq. He has also spoken by phone with prominent Kurdish leaders.

The hope is to sideline Sadr by bringing such figures together with members of Maliki's Dawa party.

The United States has also reached out through intermediaries to Grand Ayatollah Ali al-Sistani, Iraq's most revered Shi'ite cleric, according to The New York Times.

Bush mentioned Sistani at the news conference, saying that the cleric "knows that we're interested in defeating extremism, and we're interested in helping advance a unity government".

Serwer said the Bush administration must be careful to avoid the appearance of meddling too much in Iraqi politics. He said there was a further risk that if Sadr is marginalised, he may retaliate.

But Marina Ottaway, a Middle East expert at the Carnegie Endowment for International Peace, said the moderate coalition idea was "pie in the sky".

She said US efforts to court Sistani were probably a long shot and the goals of the various parties may be too divergent for such a coalition to stay together.