BAGHDAD (Reuters) -- The Iraqi parliament's biggest Sunni bloc has said it wanted guarantees of a public referendum on a U.S. security pact before it backed the deal in a vote in parliament.
Iraq's leaders say securing the Iraqi Accordance Front's blessing for the pact, which paves the way for a U.S. troop withdrawal by the end of 2011, is crucial for consensus.
The security pact replaces a UN mandate governing the U.S. military presence in Iraq, which expires at the end of this year. The current U.S. troop strength is around 150,000.
Iraq's leaders say there is unlikely to be enough time to arrange another vote on the deal if lawmakers reject it. Iraq is also unlikely to be able to organize a public referendum on the issue by year-end.
The Accordance Front said the pact must include a guarantee of a referendum and a package of political reforms that would give lawmakers more say in political decisions.
"The situation depends on two issues. The issue of a proposal for political reform, to be voted on in parliament, before the deal is put forward," said Accordance Front spokesman Salim al-Juburi.
"The second issue is that the pact will guarantee it can be voted on in a referendum," he added.
Iraqi President Jalal Talabani and parliament speaker Mahmud al-Mashhadani were holding last-minute talks with most of Iraq's political blocs to overcome objections, a member of al-Mashhadani's office said.
Sunnis are concerned their influence may wane once the Americans leave. Majority Shi'ite Iraq has a Shi'ite leadership and has good ties with neighboring Iran, a Shi'ite country.
Some 136 lawmakers of the ruling Shi'ite and Kurdish blocs in Iraq's 275-seat parliament are seen as supporting the pact, which needs a simple majority of 138 votes to pass.