The United States upped pressure on Iraqi politicians on Tuesday to reach a deal on holding elections as Washington sought to avoid delays on the pullout of thousands of troops from the country.
With President Barack Obama already grappling with whether to send more soldiers to Afghanistan, the US ambassador to Iraq warned against "slippage" in organising a January vote, which has been threatened with delays by a stalled electoral law.
His comments came after Vice President Tareq al-Hashemi, who vetoed a previous draft of the bill approved by parliament earlier this month, hinted that he would also oppose an amended version agreed on Monday.
Ambassador Christopher Hill said: "Some slippage would be okay, but we don't want a lot of slippage, so I hope they'll look very carefully at this and I hope we can get moving.
"I think what is most important is we get these elections going and get on with this process," he told reporters, without elaborating on what would constitute too long a delay.
The election, the second national ballot since the US-led invasion of 2003, is scheduled for the second half of January but cannot proceed until the electoral law receives presidential assent.
The chairman of parliament's legal committee, Baha al-Araji, said on Monday that the polls are likely to be delayed, because Hashemi, a Sunni Arab, is expected to veto the amended bill.
The new draft increases the number of parliamentary seats for Iraq's autonomous Kurdish region compared with the earlier version of the bill, but reduces the figure for Sunni Arab areas.
Hashemi said on Tuesday that he "considered the parliamentary amendments unconstitutional and unjust."
The latest draft was "very dangerous and has negative consequences for the entire political process," he said in a statement.
If a second veto is used, parliament can overturn it with a 60 per cent majority. An alliance of Shiite and Kurdish MPs would surpass that threshold with around 30 votes to spare in the 275-seat assembly.
Iraq's three-member presidential council, composed of President Jalal Talabani, a Kurd, and vice presidents Hashemi and Adel Abdel Mehdi, a Shiite, has 15 days to veto the new text.
Only one of the trio needs to veto the bill for it to be sent back to parliament.
According to a statement from his office, Talabani "hailed the decision (Monday's deal), and thought it represented the aspirations of the Iraqi people ... and enhanced the democratic process in the country."
Despite Hashemi's remarks, a UN spokeswoman said the world body remained positive that the law would pass without a veto being exercised, after UN diplomats met senior MPs and election organisers.
"The meeting regarded with optimism that the presidency council will hopefully accept the proposals discussed and soon issue a presidential decree stating the date of the parliament elections, and that there will be no reason for a second veto," she told AFP.
Secretary of State Hillary Clinton said in Washington on Monday that the US will present "a number of ideas" in a bid to resolve the stalemate, but she did not give any details.
The United States has 115,000 troops in Iraq, but that figure will drop markedly next year as all of its combat soldiers are pulled out before a complete withdrawal by the end of 2011.
However, General Ray Odierno, the top US commander in Iraq, said earlier this month that while combat troops must pull out by mid-2010, the plan was flexible and could change if the security situation deteriorates.
Hill called on Iraq's leaders to reach a consensus and pass the bill, saying: "I would just ask people to study this very carefully and to understand that any law does involve some trade-offs."
Iraq's electoral commission has warned that continued delays over passing the bill threaten to leave too little time to complete preparations by the scheduled polling date.
Parliament will be in recess until December 8 because of the Muslim feast of Eid al-Adha, probably leaving insufficient time to organise the polls for January even if MPs do approve a third version that same day.
Under Iraq's constitution, the general election must be held by January 31.