Masud Barzani, head of the Kurdistan Democratic Party, made the pledge in an interview with Al-Arabiya satellite channel on Monday.
"There are talks with various parties on steps to form the government and other matters. The main point for us is Iraq's identity and there can be no compromise on the issue of a federal, democratic, pluralist and united Iraq," said Barzani.
"Whoever is closest to these principles will be preferred by us... We have good ties with everyone, but the matter will be determined by the stances that are taken on fundamental issues," he said.
A two-thirds majority is needed in the 275-member National Assembly to form a government - a margin no coalition has yet achieved but could if it strikes an alliance with another group.
"Sunnis made a big mistake when they boycotted the election. I think it is necessary for them to participate in drafting of the constitution"
Kurdistan Democratic Party
The United Iraqi Alliance, the Shia-led religious coalition that won the 30 January poll, has yet to formally name its candidate for prime minister, although the front runner is thought to be interim Vice-President Ibrahim al-Jafari.
Interim Prime Minister Iyad Allawi, whose coalition came third, joined the running on Monday.
Jalal Talabani, leader of the Patriotic Union of Kurdistan, has been chosen to represent the Kurdish alliance in any government and hopes to become the country's next president.
Independence on hold
While the Kurds have often talked about independence, their aim now is to secure as much power as possible under a federal Iraq and they will bargain hard for as much autonomy as they can get in the constitution to be drafted by the parliament.
"There will be differences but I am sure we will reach agreement to draft a constitution which agrees with the aims of all Iraqi parties," Barzani said.
"Sunnis made a big mistake when they boycotted the election. I think it is necessary for them to participate in drafting of the constitution," he added.
Most Sunni Muslims in central Iraq did not vote through a combination of a nation-wide boycott and fear of attacks by anti-US fighters.