WASHINGTON - THE top US general and diplomat in Iraq testify in politically charged hearings in Congress on Tuesday, and face a grilling from three senators vying to inherit the war as the next US president

General David Petraeus and Ambassador to Baghdad Ryan Crocker will appear before the Senate Armed Services and Foreign Relations committees to update progress in the war and President George W. Bush's troop surge strategy.

Their keenly awaited testimony will be especially intriguing as the next US president, Republican John McCain or Democrats Barack Obama or Hillary Clinton, are heavy-hitting members of the two Senate committees.

Republicans say the surge of 30,000 extra troops into Iraq last year cut sectarian violence and stabilised the country, and they approve of Gen Petraeus's calls to pause troop withdrawals at pre-surge levels to evaluate the situation.

'If our nation abandoned efforts to stabilise Iraq, not only would terrorism follow our troops home, but it would lead to chaos in the Middle East that would wreak havoc on our national and economic security as well,' John Boehner, the top Republican in the House of Representatives, said on Monday.

A pause in troop withdrawals is likely to be unpopular with the US public, after the US death toll in Iraq passed 4,000 and as the conflict stretches into its sixth year.

Democrats praise US troops, but argue their sacrifice has not prompted serious efforts by the Iraqi government to profit from improved conditions to forge political reconciliation.

Lawmakers are expected to question Gen Petraeus and Mr Crocker about fierce recent clashes between Iraqi security forces and militias controlled by radical Shi'ite leader Moqtada Al-Sadr.

Senators will also highlight the cost of the war and ask why the United States is still paying for Iraqi domestic needs 'ranging from military training to garbage pickup', The Washington Post said.

How much money?
The Senate Armed Forces Committee last month asked the Government Accountability Office to investigate just how much money the Iraqi government has, the paper said.

'They're perfectly content to watch us spend our money while they build up these huge cash reserves from oil windfalls,' Democratic Senator Carl Levin, chairman of the Armed Services Committee, told the Post.

Hours before the hearings were to start, a draft agreement between the US and Iraq surfaced in London, according to which the two countries foresee an open-ended US military commitment in Iraq.

The document is designed to replace the current United Nations mandate, which expires at yearend, according to The Guardian newspaper, which cited a copy of a draft strategic framework agreement dated March 7 that it obtained.

According to newspaper, the agreement allows the US to 'conduct military operations in Iraq and to detain individuals when necessary for imperative reasons of security' without including a time limit.

Both Mrs Clinton and Mr Obama have vowed to end the war and bring troops home if they win November's general election. Mr McCain, a supporter of Bush's troop surge, says America has a moral duty and strategic imperative to stay and prevent chaos.

'I do not believe that anyone should make promises as a candidate for president that they cannot keep if elected,' Mr McCain said in a speech in Kansas.

'To promise a withdrawal of our forces from Iraq, regardless of the calamitous consequences to the Iraqi people, our most vital interests, and the future of the Middle East, is the height of irresponsibility. It is a failure of leadership,' he said.

Mr Obama hit back that 'John McCain was wrong about the war from the beginning, he's wrong to call for more resources in Iraq while the American people are struggling.'

Mrs Clinton said Mr McCain's policy in Iraq would mean 'four more years of the Bush-Cheney-McCain policy of continuing to police a civil war while the threats to our national security, our economy, and our standing in the world mount.' -- AFP