Three Iraqi Sunni parties have announced the formation of an alliance to contest upcoming legislative elections in December.
Tarik al-Hashimi and Adnan al-Dulaimi announce the alliance
The announcement on Tuesday that the constitution was approved cleared the way for the polls to elect a new Iraqi National Assembly.
The parties urged Iraqis to take part in the polls and to reject any calls for a boycott.
Sunni Arab parties largely boycotted last January's parliamentary elections.
The three parties hope to increase Sunni representation in a national assembly that is currently dominated by Shia Arab and Kurdish parties.
"The leaders of the following political blocs, the Iraqi Peoples Gathering, the Iraqi Islamic Party and the Iraqi National Dialogue, have agreed to run on one list under the name Iraqi Accord Front," a joint statement said.
In all, 78% of voters backed the constitution and 21% opposed it in the vote on 15 October, electoral commission officials announced on Tuesday.
The result paves the way for elections for a new four-year national assembly to be held by 15 December 2005, formally ending Iraq's period of transitional government.
Sunni figures talked of widespread fraud after hearing the final results, but the UN commended the poll.
"No" campaigners had hoped to block it by taking two-thirds of the vote in at least three provinces, but only succeeded in two.
Sunni leaders fear the constitution may split Iraq, with a Kurdish north and Shia south, depriving Sunni Arabs of access to the country's oil resources.
However, one of the three Sunni parties forming the Iraqi Accord Front had backed the charter.
The Iraqi Islamic Party encouraged Sunnis to approve the constitution after Shia and Kurdish political leaders agreed to consider further revisions after the elections in December.
The party's secretary general, Tarik al-Hashimi, told Qatari Al-Jazeera television that its support for the constitution did not mean it would accept the "attempt to distort the results of the voting in any Iraqi governorate".
Mr Hashimi was also troubled by the disparities between provinces where Sunni Arabs were the majority, and those where Shias and Kurds dominate.
"The split among the Iraqis on the draft constitution is very clear and this portends serious signs concerning a fateful issue over which no people in the world have been as divided as this," he said.