The United States’ pleas for Iraq’s government to decide “within weeks” whether American troops should stay beyond a year-end deadline to leave will not be met, Iraqi politicians say, complicating plans for the U.S. military withdrawal.

The Iraqi politicians attributed this to a confluence of domestic issues. Political brinkmanship, popular unrest and mounting mistrust among lawmakers have conspired to make a decision on a lasting U.S. military presence politically untouchable for Iraqi politicians for months to come.

Although Prime Minister Nouri al-Maliki has been seen as leaving the door open to some continued U.S. support, he has also asserted that Iraq no longer needs military help from the Americans. Any decision to extend the U.S. troop presence into 2012 would need approval from the Iraqi parliament. Compounding the problem is a wave of assassinations of government officials and threats by extremists of further violence should Iraqi leaders vote to extend the U.S. military presence.

“There is no certain time or certain date to decide on the U.S. military, and we will not be in a hurry to take a decision,” Osama al-Nujaifi, the speaker of parliament, said in an interview.

A growing chorus of military strategists in Washington would like a deal allowing at least some continued U.S. military presence in Iraq. Amid the broad unrest across the Middle East, they say, a U.S. foothold in Iraq is critical to help ensure stability in that country and to keep Iran and other potential aggressors in check.

But publicly the Obama administration has been adamant that any continued troop presence — beyond a couple of hundred military advisers attached to the U.S. Embassy — would be authorized only if Iraq requests help.

The lack of clarity about whether troops would be asked to stay or go is what Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, seemed intent on avoiding when he visited Iraq last month and requested its leaders to decide “within weeks ” whether they wanted an extended U.S. presence.

An elaborate U.S military withdrawal is set to swing into high gear by late summer, with the removal of nearly 50,000 troops and 63,000 contractors; the closure of nearly 100 bases; and the hauling away or disposal of about 1 million pieces of equipment accumulated during eight years of conflict.

Gen. Babakir Zebari, a Kurd who holds a position roughly equivalent to that of the U.S. Joint Chiefs chairman, has said repeatedly that Iraq’s army “will not be ready to control Iraq until 2020.”

If Iraqi leaders decide late in the year to request that some U.S. troops or equipment stay, military officials say, it would entail significantly altering or even reversing the course and could compound security concerns and costs.

Ali al-Dabbagh, a government spokesman, insisted that Iraq would hold the course and be fine after U.S. forces leave.

“We highly understand that there is a legitimate worry from Washington and the Pentagon that the situation in Iraq, post-2011, might face some difficulties due to a so-called ‘power vacuum,’ ” Dabbagh said in an interview. “Definitely, we are not excepting of this theory. We frankly told Admiral Mullen that their presence here will be costly for them and definitely costly for us.”

“Keeping a few thousand, that might cause retaliatory reaction that may escalate,” he said.

Anti-American Shiite cleric ­Moqtada al-Sadr, whose support was critical for Maliki to form a new government, has warned that keeping U.S. troops in the country would amount to a continued “American occupation” and that such an agreement would constitute the basis for renewed armed resistance to U.S. and Iraqi forces. Sadr’s followers have also threatened to break with the government.

On the other hand, Maliki said in a recent televised appearance here that Iraq’s air force will not be ready by next year to protect the country from foreign threats. He said Sunday that representatives of Iraq’s political parties should meet to discuss the troop withdrawal issue. In his interview, Dabbagh also made a cryptic remark that continued military cooperation with the United States may be acceptable if it “could take other forms, of empowering the system or the democracy in Iraq.”

Similarly tentative statements have emanated from fellow Shiites as well as Sunnis and Kurds. Some close observers of Iraqi politics said these statements may represent the opening salvos of the coming debate and a common ground for a compromise.

“The prime minister is the commander in chief, and we must hear from him whether he is with [the U.S.] or against,” said Ayad Allawi, head of the Iraqiya bloc, the largest political coalition in parliament. “Unfortunately, we believe neither the Iraqi army nor the police are ready to face the responsibility and shoulder it alone.”

“The fact is most of our weapons are American, and they need maintenance and repair and training and supplies,” said Abbas al-Bayati, a lawmaker in Maliki’s coalition. “The real position [of the prime minister], we will hear about it when we get closer to the end of the year.”

For now, Maliki appears to be most focused on meeting a pledge to present a 100-day plan by June to improve government services. That initiative, launched after protests here in February, is intended to head off domestic unrest of the kind sweeping the Middle East and North Africa.

Maliki also must resolve a standoff over who should head Iraq’s military, police and intelligence services. An unfulfilled deal reached in December requires each to be led by a different faction. That team of Sunni, Shiite and Kurdish officials would share responsibility as part of the government’s effort to secure Iraq after U.S. troops leave.

Abdul Hussein Abtan, a Shiite legislator from the Islamic Supreme Council of Iraq, said that no lawmaker wants to be the first one viewed as considering supporting an extended U.S. troop presence. “Everybody wants to stay away from this topic,” he said. “I don’t want to exaggerate, but this issue might cause the collapse of the parliament and of the entire government.”

Special correspondents Aziz Alwan and Asaad Majeed contributed to this report.