As Iraq braces for an Oct. 15 national referendum on the charter, many Sunni groups, including al-Hashemi's Iraqi Islamic Party, have urged people to vote "no." The constitution risks being rejected if there is a two-thirds "no" vote in at least three provinces.

"It is possible to make changes until the last minute," al-Hashemi told reporters during a visit to Turkey. "We will strive for changes until the last minute."

Al-Hashemi said the draft contained many flaws which his party wanted rectified, including what he said was confusion over Iraq's Arab identity, uncertainty over the powers of federal regions and rules concerning constitutional amendments.

Sunnis object to the constitution's reference to Iraq as "part of the Islamic world" rather than the Arab world, a concession to non-Arab Kurds.

"The constitution is not fair, the constitution is not balanced and is full of loopholes," he said.

Sunni Arabs, who dominated the country under Saddam Hussein, are deeply concerned that they are losing power to the country's majority Shiites and ethnic Kurds in the north. Majority Sunni Turkey, which is battling pro-autonomy Kurdish guerrillas in its own southeast, is worried that Iraq could fragment along ethnic lines.

Al-Hashemi is in Turkey to discuss the referendum with Foreign Minister Abdullah Gul and other leaders.

A coalition of Sunni groups boycotted the Jan. 30 election that chose Iraq's transitional government.