A predominantly Sunni Muslim group announced Wednesday it will withdraw from Iraq's election if the vote is not postponed to allow for ballot preparations in areas where security remains tenuous.

The 216-member National Front For Iraq's Unity (search), a group of several Sunni Muslim tribes and political parties, also threatened to pull out in protest of its leader's detention by U.S. troops.

A statement from the front said its leader, Hassan Zeidan Khalaf al-Lahibi, was detained on Dec. 31 and that he's still being held. It did not say why he was detained. The U.S. military did not immediately respond to a request for comment.

Some political parties and even several interim government officials have called for the vote to be pushed back because of fears the lack of security — especially in mostly Sunni areas — will keep voters away from the polls, skewing the results.

The vote will choose a 275-member National Assembly that will draft a permanent constitution for Iraq.

If the elections are held on schedule "our front and its coalition of political groups will withdraw from participating in elections," the group said.

Its withdrawal would not be seen as a significant setback since its candidates are not well-known politicians and it is just one of more than 100 individual parties and coalitions running about 6,000 candidates altogether.

Sunni Arab clerics have called for a boycott of the vote, and Iraq's largest Sunni political party, the Iraqi Islamic Army, announced last month it was pulling out of the race. Continued violence has seen insurgents kill scores of Iraqi security troops and several election officials in recent weeks.