By Arshad Mohammed

WASHINGTON (Reuters) - The United States should prepare to use greater military power and covert action in Syria to help forge a political settlement to end the country's civil war, according to a bipartisan report to be released on Wednesday.

Produced by a task force led by former U.S. Secretary of State Madeleine Albright, a Democrat, and former U.S. National Security Adviser Stephen Hadley, a Republican, the report amounts to a bipartisan rejection of President Barack Obama's decision to limit U.S. military engagement in the nearly six-year civil war.

Largely drafted before Republican Donald Trump's victory over Democrat Hillary Clinton in the Nov. 8 U.S. presidential election, the paper, which has not been presented to Trump, makes a case for deeper U.S. involvement in the Middle East.

"Isolationism is a dangerous illusion," said the report, which was obtained by Reuters on Tuesday. It calls for outside nations to help wind down conflicts in Iraq, Libya and Yemen and back home-grown reform throughout the region.

Its key recommendation for Syria may be moot when Trump takes office on Jan. 20 if government forces seize eastern Aleppo, the opposition's most important urban stronghold. Syrian President Bashar al-Assad has been dramatically strengthened by Russian military support over the past 14 months.

"The United States should be prepared to employ air power, stand-off weapons, covert measures and enhanced support for opposition forces to break the current siege of Aleppo and frustrate Assad's attempts to consolidate control over western Syria's population centers," the report said.

It is unclear what policy Trump will pursue on Syria. In an Oct. 26 interview, he told Reuters a more aggressive military policy advocated by Clinton could "lead to World War Three," because of the potential for conflict with Russian forces.

Trump also made clear his priority was fighting Islamic State militants rather than unseating the Syrian president, saying: "Assad is secondary, to me, to ISIS."

The Syrian army and its allies aim to seize all of eastern Aleppo before Trump takes office on Jan. 20, keeping to a Russian-backed timeline after big gains in recent days, a senior official in the military alliance supporting Assad said.

The United States has two main lines of effort in Syria: a covert CIA operation that backs opposition forces trying to oust Assad and a wider military operation that uses air strikes and special forces to target Islamic State and al Qaeda fighters.

The report argues U.S.-backed opposition forces should also be allowed to strike Assad government targets.

Asked whether a greater U.S. military effort might yield a bloodier proxy war rather than a political solution, Hadley told Reuters: "It may not work. But one of the things we know is that what's now going on isn't working."

(Editing by Yara Bayoumy and Jeffrey Benkoe)