BAGHDAD - Iraq's Sunni Arab vice president vetoed an election law on Wednesday, prompting poll workers to halt some preparations and casting new doubt on whether the vote can take place in January.

The United States expressed disappointment and urged Iraqi parliamentary leaders to pass the law quickly to prevent an election postponement that could affect U.S. plans to end combat operations next August and pull out fully by 2011.

Vice President Tareq al-Hashemi said his veto of one article of the law was unlikely to delay the poll. But his actions could open the door to a fresh round of debate over the legislation that only won parliamentary approval after protracted wrangling.

The U.S. military commander in Iraq on Wednesday said he did not have to decide until April or May on whether to push back the end of U.S. combat operations in Iraq due to a potential poll delay.

Hashemi, casting himself as a champion of Sunni Arab rights, defended his move as giving Iraqi refugees a voice.

My suggested amendment is to give justice to all Iraqis living abroad, not just Iraqis displaced in neighboring countries, he told a news conference.

Many Iraqis abroad are, like Hashemi, members of Iraq's once-dominant Sunni Muslim community. Many of them fled when the country descended into sectarian warfare after Sunni dictator Saddam Hussein was ousted in the 2003 U.S.-led invasion, propelling Iraq's Shi'ite majority to political dominance.

Prime Minister Nuri al-Maliki, a Shi'ite, rebuked Hashemi and said his move was a serious threat to the democracy and political process in Iraq. He urged the election commission to continue poll preparations.

One official from Iraq's electoral commission, which had already complained of little time to prepare for the election, said it had suspended all work.

Another official said work related to candidate lists and distribution of some seats had been stopped, but that other work, such as the training of poll workers, continued.

It is really hard to see how a delay of the elections can be avoided, said Reidar Visser, editor of the Iraq-focused website www.historiae.org.

The fear is that multiple issues will come up for discussion once the bill gets back to parliament. Already, some Iraqi politicians are talking about the whole process having gone back to square one.

'DARK TUNNEL'

U.S. State Department spokesman Ian Kelly said the military withdrawal was on track for now but it was in everybody's interest to stick to the timetable.

We're disappointed at these developments ... we urge Iraqi leaders in parliament to take quick action to resolve any of the outstanding concerns that have been expressed so elections can go forward, he told reporters.

Hashemi, one of Iraq's two vice presidents and part of a presidential council that has veto power over legislation, wants 15 percent of parliamentary seats for minorities and Iraqis displaced internally and abroad.

The electoral law allocates five percent of the 323 seats in the next parliament to minorities, such as Christians, and to Iraqis displaced from their homes.

But it does not spell out how the two million Iraqi refugees estimated to be living abroad will be represented.

Hashemi said the issue could be resolved in a single session of parliament and that electoral authorities should continue preparing without any expectation of a delay in the poll date.

But other politicians, wary of parliamentary squabbling over the issue, were skeptical.

The election law veto threatens the whole political process and the presidency council's responsibility is to safeguard the constitution -- not to push the country into a dark tunnel, Haidar al-Ibadi, an influential lawmaker from Maliki's Dawa party, told state television.

The vote is viewed as a major milestone as Iraq emerges from 6-1/2 years of bloodshed and stands on its own feet while U.S. forces withdraw.

(Additional reporting by Ahmed Rasheed and Khalid al-Ansary; Writing by Deepa Babington; editing by Michael Christie and Philippa Fletcher)

Iraq