Tariq al-Hashimi, secretary-general of the Iraqi Islamic Party, told Aljazeera on Sunday that his party would reject the constitution if it was against the movement's principles, dealing a further blow to hopes of a political process involving all the country's communities.
"We will reject the legitimacy of the results of the elections. The national assembly will be without legitimacy. We will reject it and we will also reject the constitution that it will draw up if it is against our principles," he said.
"We think that a situation marked by chaos and violence does not favour holding elections that will create a national assembly and even draw up the constitution.
"This assembly will not be representative of all categories of Iraqi society," al-Hashimi told Aljazeera.
He also echoed previous calls by his party for the election to be postponed and warned that other groups would pull out soon.
"Several parties, movements and groups who have still not taken a decision on this issue seriously want to delay the elections. We expect other withdrawals in the near future," he said.
Meanwhile, US Secretary of State Colin Powell on Sunday predicted a Shia victory in the planned Iraqi elections.
The statement came amid growing indications that Sunni Arabs would either boycott the polls or would be prevented from taking part due to growing violence, which Powell said was not likely to stop any time soon.
Powell foresees a Shia victory in
the upcoming elections
"The new government that comes into place in Baghdad, the transitional national assembly, will be majority Shiite [Shia]," Powell said on NBC's Meet the Press show.
"That's the majority of the population."
According to the Encyclopaedia Britannica, Shia Muslims make up more than 53% of Iraq's population, concentrated mostly in the southern and central parts of the country.
Powell also said he felt it was unlikely Shia control of Iraq's future government would mean it would be run from Tehran.
"My sensing right now is that, even though there may be Iranian influence - and Iranians will try to influence this, of course - there is sufficient difference and past serious disagreements and conflicts between Iranian and Iraqi Shia," he said.
Given that, Iraqi Shia "will stand on their own two feet," he concluded.
Powell did not spell out reasons for his confidence, but US and other Western diplomats have been in contact with aides to Iraq's most prominent Shia cleric, Grand Ayat Allah Ali al-Sistani, and other Shia officials to discuss the elections and future political arrangements, officials said.
Al-Sistani was born in Iran and
studied theology in Qum
Although seen as a moderate influence in Iraqi politics, al-Sistani was born in Iran and studied theology in the central Iranian city of Qum.
Shia political leader Abd al-Aziz al-Hakim, whose Unified Iraqi Alliance is expected to do well in the upcoming polls, assured visiting US senators last month that Iran would not be allowed to meddle in Iraqi affairs.
But he is closely tied to the Supreme Council for Islamic Revolution in Iraq, an opposition group formed in Iran in 1982 and backed by it for many years.
However, a number of Iraqi and Arab officials expressed concern about Iranian influence in the war-torn country.
The Iraqi interim government said last month that Iran is "the source of terrorism in Iraq".
Jordan's King Abd Allah II has also charged that Iran was stoking violence in Iraq and trying to set up a Shia belt from Iran to Lebanon through Iraq and Syria
Calls for delay
Former Iraqi foreign minister Adnan Pachachi, who now heads the Sunni-dominated Iraqi Independent Democrats Party, called on Sunday for delaying the vote, saying elections under current circumstances would "leave a large segment of the population disenfranchised and many regions underrepresented".
Pachachi said delaying the election for a few months could help avoid a situation in which the legitimacy of the vote would be questioned.
"Nothing remotely like electioneering takes place in Iraq, even in relatively peaceful areas in the south and north," the veteran politician wrote in The Washington Post.
"For candidates to announce mass rallies would be to issue an open invitation for terrorists to attack."