WASHINGTON (Reuters) - The United States needs to regain its leadership role in the world, Republican Jeb Bush will say in a speech on Wednesday, while asserting that President Barack Obama has been inconsistent and indecisive in carrying out American foreign policy.

Mr Bush's speech at the Chicago Council on Global Affairs will be his first major foray into foreign policy since he announced in December that he is considering a run for the 2016 Republican presidential nomination. "The great irony of the Obama presidency is this: Someone who came to office promising greater engagement with the world has left America less influential in the world," Mr Bush will say, according to speech excerpts that were provided to Reuters.

The former Florida governor is casting a wide net for advice on national security. An aide provided to Reuters a diverse list of 20 diplomatic and national security veterans who will be providing informal advice to Mr Bush in the coming months.

Many of them are from past Republican administrations, including those of his father and brother, former presidents George H. W. Bush and George W. Bush, as well as that of former president Ronald Reagan.

The list includes people representing a wide spectrum of ideological views in the Republican Party, from the pragmatic to the hawkish. It includes Mr James Baker, known for his pragmatism in key roles during the Reagan and George H. W. Bush presidencies, and former World Bank President Paul Wolfowitz, a hawk as deputy defense secretary who was an architect of Mr George W. Bush's Iraq policy.

Among others are two former secretaries of Homeland Security, Mr Tom Ridge and Mr Michael Chertoff, former national security adviser Stephen Hadley and a deputy national security adviser Meghan O'Sullivan, as well as two former CIA directors Porter Goss and Michael Hayden.

With polls showing Mr Bush is a front-runner among Republican candidates jockeying for the 2016 nomination, his aim is to set his own course on US foreign policy without getting entangled in a debate about the legacy of his father and older brother.

Mr Bush's Chicago speech is the second in a series of appearances designed to outline the foundation for what is likely to be a presidential campaign. Two weeks ago in Detroit, he discussed his views on reducing income inequality and bolstering the US economy.

His Chicago speech comes as the United States grapples with the threats posed by Islamic State militants and Russia's aggression in eastern Ukraine.

Mr Obama has relied heavily on airstrikes against Islamic State in Iraq and Syria targets, but the militants still retain large swathes of territory in both countries. Washington has joined with European allies to impose sanctions on Russia that have had an impact but have yet to force Moscow to pull back. "My goal today is to explore how America can regain its leadership in the world, and why that leadership is more necessary than ever," Mr Bush will say.

Mr Bush will say that American leadership projected consistently and "grounded in principle" has been a benefit to the world.

"Under this administration, we are inconsistent and indecisive," he will say. "We have lost the trust and the confidence of our friends. We definitely no longer inspire fear in our enemies."

He will take aim at Mr Obama's 2013 decision to back away from the "red line" he established against Syrian use of chemical weapons a year earlier as well as the Obama administration's "reset" in US relations with Russia, a policy carried out by then Secretary of State Hillary Clinton, the favorite for the Democratic presidential nomination in 2016.

"They draw red lines, then erase them," he will say. "With grandiosity, they announce resets and disengage."

Mr Bush will say it is critical that the United States adapt to the threats of the 21st century. "America does not have the luxury of withdrawing from the world - our security, our prosperity and our values demand that we remain engaged and involved in often distant places," he will say.

His list of advisers suggests a willingness to listen to a variety of views from people with long experience, including former World Bank President Robert Zoellick.

Others include Ms Paula Dobriansky, a former undersecretary of state, Ms Kristen Silverberg, a former US ambassador to the European Union, Mr Lincoln Diaz-Balart, who was a long-time member of the House of Representatives from Florida, and Mr John Hannah who was then Vice-President Dick Cheney's national security adviser.