WASHINGTON (AFP) — The US Senate is expected to vote as early as Tuesday on a Bosnia-style plan to subdivide Iraq on ethnic lines, touted by backers as the sole hope of forging a federal state out of sectarian strife.

Though the measure is non-binding, and would not force a change in President George W. Bush’s war strategy even if it passes, the vote will provide a key test of an idea drawing rising interest in Washington.

Advocates say the plan, championed by Democratic senator and presidential hopeful Joseph Biden, offers a route to a political solution in Iraq that could allow US troops to eventually go home without leaving chaos behind.

A loose autonomous federation of Kurdish, Shiite and Sunni entities might look good on paper, but critics charge it ignores Iraq’s ethnic stew, such as cities where ethnic groups live side-by-side and inter-marry, and are not divided by lines on a map.

“Critics have come along and said ‘I don’t like your plan,'” Biden said, adding: “if you don’t like Biden’s proposal, what is your idea?”

The plan, drawn up with former Carter administration foreign policy expert Leslie Gelb, would provide for a federal system as permitted by Iraq’s constitution, stop Iraq from becoming a failed state and:

– Separate Iraq into Kurdish, Shiite and Sunni entities, with a federal government in Baghdad in charge of border security and oil revenues.

– Aim to defuse sectarian violence by offering Sunnis a share of oil revenues.

– Boost reconstruction aid and debt relief.

– Launch an international diplomatic effort to rally the world’s great powers and Iraq’s neighbors to the new federation’s cause.

The plan, offered as an amendment to a defense policy bill, already has achieved what many other Iraq war measures have failed to do: attract support from across the political chasm carved in Washington by the war.

Several Republicans, who back Bush’s troop surge strategy, but bemoan political deadlock in Baghdad, have signed on.

“We have a flawed political design that we are pushing currently in Baghdad,” said Republican presidential longshot Senator Sam Brownback, one of 11 co-sponsors of the bill.

Republican Senator Kay Bailey Hutchison looked for inspiration to the Dayton Peace Accords which led to the creation of a semi-autonomous Muslim-Croat federation and a Bosnian Serb Republic.

“I think what we have seen in Bosnia is a lessening of tensions when there is a capability for the security forces, the educational and the religious sects to have their own ability to govern within themselves,” she said.

Critics, who have included the White House, have argued Biden plan is a recipe for more chaos in Iraq.

US ally Turkey would oppose such an initiative, fearful of unrest among its Kurdish population, they say, adding that a partitioned Iraq would lead outside powers like Iran and Saudi Arabia to bolster rival ethnic militia.

Other critics say frontier drawing in the Middle East by western powers has caused enough historical heartache, and it should be up to Iraqis to shape their future.

Some also say that partitioning Iraq, even if Baghdad remains whole, could encourage ethnic cleansing.

US ambassador to Baghdad Ryan Crocker backed devolving of power to Iraqi regions, but opposed a formal partition during an appearance in Congress this month.

“Baghdad, in spite of all of the violence it has seen and all of the population displacements, remains a very mixed city, Sunnis and Shia together,” Crocker said.

“Any notion that that city of over five million people can be neatly divided up or painlessly cleansed of a huge number of people is just incorrect.”

The bipartisan Iraq Study Group, which delivered recommendations in December warned partition could trigger mass population flows, the collapse of the fragile Iraqi security forces and ethnic cleansing by strengthened militias.

But Biden argued that all other options have failed, and says Iraq’s ethnic groups are already separating.

“President Bush, and many Democrats continue to cling to choice number one,” he said in a campaign mailing to supporters at the weekend, arguing US troops could not “build or force unity where none exists.”