WASHINGTON (AP) — President Barack Obama asked Congress on Wednesday to authorize military force to "degrade and defeat" Islamic State forces in the Middle East without sustained, large-scale U.S. ground combat operations, setting lawmakers on a path toward their first war powers vote in 13 years.

The initial reaction was bipartisan skepticism. Republicans expressed unhappiness that Obama chose to exclude any long-term commitment of ground forces, while some Democrats voiced dismay that he had opened the door to deployment at all.

In a letter accompanying draft legislation, Obama said approval of his request would "show the world we are united in our resolve to counter the threat" posed by fighters seeking establishment of an Islamic State.

The White House said the president would speak publicly about his plans at midafternoon.

Under Obama's proposal, the use of military force would be authorized for three years, unbounded by national borders. The fight could be extended to any "closely-related successor entity" to the Islamic State organization that has overrun parts of Iraq and Syria, imposed a stern form of Sharia law and executed several hostages it has taken, Americans among them.

The 2002 congressional authorization that preceded the American-led invasion of Iraq would be repealed under the White House proposal, a step some Republicans were unhappy to see. But a separate authorization that was approved by Congress after the Sept. 11, 2001, terror attacks would remain in force, to the consternation of some Democrats.

At the heart of the debate, the struggle to define any role for American ground forces is likely to determine the outcome of the administration's request for legislation. White House spokesman John Earnest said the proposal was intentionally ambiguous on that point to give the president flexibility, but the approach also was an attempt to bridge a deep divide in Congress.

While asking lawmakers to bar long-term, large-scale ground combat operations like those in Afghanistan and Iraq, Obama said he wants the flexibility for ground combat operations "in other more limited circumstances." Those include rescue missions, intelligence collection and the use of special operations forces in possible military action against Islamic State leaders.

Whatever the outcome, Obama's request puts Congress on the path toward a vote that could reverberate unpredictably for years.

A post-9/11 request from then-President George W. Bush for authorization to use military force against Iraq was intensely controversial, and it played a role in Obama's successful campaign for the White House in 2008.

His chief rival for the Democratic nomination, then-New York Sen. Hillary Clinton, voted in favor of the Bush proposal. Obama, who was not in Congress at the time of the vote, said later he would have opposed it, and he made it an issue in the presidential race.

Clinton, who served four years as Obama's secretary of state and is now a likely candidate for president in 2016, had no immediate reaction to the proposal.

Lawmakers were not as reticent, although outright supporters of the president's plan were relatively scarce.

House Speaker John Boehner, R-Ohio, expressed doubt it would "give our military commanders the flexibility and authorities they need to succeed and protect our people."

He said changes are likely before the measure comes to a vote, although one House committee set an initial hearing for Thursday.

Senate Majority Leader Mitch McConnell, R-Ky., like Boehner, said the proposal would receive serious consideration.

Another senior Senate Republican, James Inhofe of Oklahoma, said any legislation "should not be limited by time. It should not be limited by geography, and it should not tie the hands of our military commanders with methods and tactics that limit needed flexibility."

Democrats had a different reason to question the president's proposal.

The House Democratic leader, Rep. Nancy Pelosi of California, issued a statement that refrained from endorsing Obama's request. It said Congress should act judiciously and promptly to pass legislation "narrowly tailored" to the fight against Islamic State fighters. She has said previously she opposes deploying U.S. "boots on the ground."

Patrick Leahy of Vermont, the Senate's longest-serving Democrat, cautioned that any legislation must be in a form that avoids "repeating the missteps of the past and that does not result in an open-ended authorization that becomes legal justification for future actions against unknown enemies, in unknown places, at unknown times."

In a letter to lawmakers accompanying the three-page draft legislation, Obama referred to four American hostages who have died in Islamic State custody — at least three of them beheaded. He said the militant group, if left unchecked, "will pose a threat beyond the Middle East, including to the United States homeland."

Among the four hostages was Kayla Mueller, a 26-year-old humanitarian worker whose death under unknown circumstances was confirmed Tuesday.

In the past, Obama has cited congressional authorizations from 2001 and 2002 to justify his decision to deploy more than 2,700 U.S. troops to train and assist Iraqi security forces and conduct airstrikes against targets in Iraq and Syria.

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