(Reuters) - President Barack Obama came under pressure from U.S. lawmakers on Wednesday to persuade Iraqi Prime Minister Nuri al-Maliki to step down over what they see as failed leadership in the face of an insurgency threatening his country.

As Obama held an hour-long meeting with congressional leaders on U.S. options in Iraq, administration officials joined a chorus of criticism of Maliki, faulting him for failing to heal sectarian rifts that militants have exploited.

Army General Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff, told a congressional hearing that Maliki's Shi'ite-led government had asked for U.S. air power to help counter Sunni militants who have overrun northern Iraq.

The general did not say whether Washington would meet the request. But Dempsey signaled that the U.S. military - apparently much like Obama - was in no rush to launch airstrikes in Iraq, citing the need to clarify a chaotic situation on the ground so any targets could be selected "responsibly."

In Oval Office talks, Obama briefed the lawmakers on efforts to get Iraqi leaders to "set aside sectarian agendas," reviewed options for "increased security assistance" and sought their views, the White House said.

A senior administration official said afterward that Obama did not lay out a course of action at the meeting and had yet to make a final decision.

At the same time, the Obama administration has quietly started consulting Congress about a plan for redirecting some current intelligence funding to help finance expanded U.S. operations in Iraq, a U.S. national security source said.

The United States, which invaded Iraq in 2003 to topple President Saddam Hussein and withdrew its troops in 2011, has said Iraq's government must take steps toward sectarian reconciliation before Obama will decide on any military action against the insurgency led by the Islamic State of Iraq and the Levant, or ISIL, an al Qaeda splinter group.

Maliki has so far shown little willingness to create a more inclusive administration.

"The Maliki government, candidly, has got to go if you want any reconciliation," said U.S. Senator Dianne Feinstein, Democratic chairwoman of the Senate Intelligence Committee.

'HIS TIME IS UP'

Republican Senator John McCain, speaking in the Senate, called for the use of American air power, but also urged Obama to "make it make very clear to Maliki that his time is up."

The Obama administration has not openly sought Maliki's departure, but has shown signs of frustration with him.

"This current government in Iraq has never fulfilled the commitments it made to bring a unity government together with the Sunnis, the Kurds and the Shia," Defense Secretary Chuck Hagel told the congressional hearing.

White House spokesman Jay Carney said Maliki had not done enough "to govern inclusively and that has contributed to the situation and the crisis that we have today in Iraq."

He stopped short of calling for Maliki - in power for eight years and the effective winner of a parliamentary election two months ago - to resign. Asked if Maliki should step down, Carney told reporters: "That's not, obviously, for us to decide."

Although Obama is continuing to deliberate on what action to take, the president - who won the 2008 election on a platform calling for an orderly withdrawal from the unpopular war in Iraq - has ruled out sending troops back into combat there. Some in the anti-war camp of Obama's Democratic Party oppose any military action that could drag the United States back into the conflict, and he is apparently wary of such a risk.

Senate Republican leader Mitch McConnell said after the meeting with Obama that ISIL's operations in Iraq and Syria "represent a grave threat" to U.S. interests. "Unfortunately, Iraqi security forces are now less capable than when the president withdrew the entirety of our force (at the end of 2011)," McConnell said in a statement.

Much attention has been focused on the possible use of airstrikes, either by planes or unmanned drones, but U.S. officials have made clear they are concerned about the risk of hitting the wrong targets and causing civilian casualties.

Options under consideration include stepped-up training of Iraqi forces, possibly with U.S. special forces, accelerated delivery of weapons and increased sharing of intelligence.

U.S. officials, speaking on condition of anonymity, said Iraq's request for air support included drone strikes and increased surveillance by U.S. drones, which have been flying over Iraq for some time.

Recent assertions by U.S. officials that any U.S. military role would be targeted and selective suggest that if Obama gives the go-ahead for strikes, it might involve limited attacks with unmanned drones like those used in Pakistan and Yemen.

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