Jeb Bush speaks in Tallahassee on Feb. 10. (Phil Sears/AP)

Shortly before Jeb Bush made his first moves toward a presidential campaign, he took to a stage in Miami and tore into President Obama on foreign policy.

Bush described in a speech in December how the United States has kept thousands of troops deployed on the Korean Peninsula to help avoid a major conflict in Asia. But as he built up to his attack line against Obama, the former Florida governor stumbled — reaching for a word that threatens to loom large over his expected White House run.

“This president missed an opportunity to do the exact same thing in, in, in, um, Iraq,” he said.

Bush, a son and brother of former presidents, finds himself in a unique and difficult position within the Republican field as he works to formulate a foreign policy agenda. Voters and rival campaigns are watching closely to see how heavily he leans on veterans of the two past Bush administrations — and, in particular, how he addresses the ongoing instability in Iraq, the country where his father, George H.W. Bush, fought a war and the country his brother George W. Bush would later invade and occupy.

Jeb Bush is expected to offer some clues to his foreign policy views in a speech Wednesday at the Chicago Council on Global Affairs. More than 700 people are expected to attend the morning address, according to organizers.

“We’re on the verge of the greatest time to be alive in American history. I honestly believe that,” he told reporters in Florida last week. “But we have some big, hairy, complicated things we need to fix, and one of those is what the role of America is in the world to protect our safety and security, but also to promote security and peace around the world.”

Aides declined to preview Bush’s Chicago speech, and they refused to name his advisers or describe his process for developing thoughts on global affairs.

Bush is only now beginning to fully articulate his worldview. It remains unclear where he might draw distinctions with the records of his father and brother, other than saying that he aims to “talk about the future” rather than the past. Both Bush presidencies were defined in part by conflict in Iraq, with the second President Bush’s war there resulting in a long and costly occupation.

Many conservatives are “waiting to see how he splits the difference between what he perceives — or what his advisers perceive — to be the pluses and minuses of his father’s and brother’s administrations,” said Gary J. Schmitt, a former Reagan administration official now with the American Enterprise Institute. “My view would be that his brother’s principles fit the time. The question is whether Jeb Bush can improve on carrying out those principles.”

Rick Wilson, a Florida-based GOP strategist, said: “We go in cycles in this country. We hate foreign affairs and foreign entanglements and foreign engagements right until somebody punches us in the face. I can’t speak to Jeb’s foreign policy direction, but what could be worse than the present alternative?”

Peter D. Feaver, a former National Security Council official under George W. Bush with responsibility for Iraq, said Jeb Bush appears to be adopting a “big-tent approach” as he reaches out to a cross section of GOP experts. Bush is consulting with people including Richard N. Haass, president of the Council on Foreign Relations and a former State Department official during George W. Bush’s first term; former deputy secretary of state and former World Bank president Robert Zoellick; and Meghan O’Sullivan, a former George W. Bush national security adviser on Iraq, according to another Republican foreign policy expert who has spoken with Bush but is not aligned with him or any other campaign and asked for anonymity in order speak frankly about those talks.

Bush has also consulted with former secretary of state Condoleezza Rice, but his interactions with her are “more complicated because if she’s too involved I think there’s a sensitivity that it would be a carbon copy of his brother’s administration,” the foreign policy expert said.

Said Feaver: “He’s not giving in to the idea that anyone associated with the Iraq war is out of consideration. That’s not practical. Keeping them out would reinforce a cartoon critique of the former president’s Iraq policy.”

Democrats have long blamed George W. Bush with a failed execution of the Iraq war.

“If you thought George Bush’s foreign policy made the world less safe, then you’re going to really hate Jeb Bush’s approach,” Mo Elleithee, communications director for the Democratic National Committee, wrote in an e-mail. “Even with the benefit of hindsight, he’s one of the few people left who still stands by the decision to rush into a war in Iraq based on false information, even when it took resources away from the hunt for Al Qaeda in Afghanistan.”

Obama won the White House in 2008 in part because of his opposition to the war, which had its roots in a 2002 speech he gave as an Illinois state senator opposing military action in Iraq.

The presumptive 2016 front-runner on the Democratic side, former secretary of state Hillary Rodham Clinton, would be formidable on foreign policy in the campaign but has her own vulnerabilities. Her 2002 Senate vote in favor of the Iraq war haunted her throughout her failed 2008 presidential campaign as the war dragged on. The U.S.-backed Iraqi government was weak and poorly equipped to handle the civil war that U.S. military action had helped to unleash, and American popular opinion had turned to view the war as a mistake.

Clinton did not call her vote a mistake until she wrote last year in her State Department memoir, “Hard Choices,” that “I still got it wrong.”

Over the course of his brother’s presidency, Bush frequently expressed support for the war. Just as the Iraq conflict began in 2003, he told Florida reporters that “in his heart, I know he is doing what he thinks is right, and I concur with him.”

He traveled to Iraq and Afghanistan with other Republican governors in April 2006 to visit U.S. troops, and they appeared together in the White House Rose Garden upon their return.

In 2013, nearing the 10th anniversary of the start of the war, Bush told NBC that “history will be kind to my brother the further out you get from this and the more people compare his tenure to what’s going on now.”

He has sharply criticized Obama’s foreign policy since emerging as a potential presidential candidate.

In his Miami speech in December, Bush faulted Obama’s “indecisiveness, his concern for domestic political considerations in the formulation of foreign policy, his seeming inability to engage in the personal diplomacy needed to build the trust to be able to forge consensus in foreign policy — but what the heck, I might as well mention domestic policy as well in that regard.”

The speech was hosted by the U.S. Cuba Democracy PAC, a group strongly opposed to Obama's decision to restart diplomatic relations with Cuba. Bush has long aligned himself with the influential Cuban American community in South Florida.

“Instead of lifting the embargo, I would argue that we should strengthen it to put pressure on the Cuban regime,” Bush said, adding later that “I am not a pessimist about the future of Cuba” but that “the Castro brothers are on the wrong side of history.”

His views on Cuba are shared by Sen. Marco Rubio (R-Fla.), a Bush protege who is also considering a 2016 campaign. But they are at odds with the views of Sen. Rand Paul (R-Ky.), another potential candidate, and a growing number of GOP lawmakers, mostly from farming states, who are working with Democrats to ease travel restrictions and lift the embargo.

Bush sprinkled his December speech with references to Latin America. He equated “Chavistas” — supporters of the late Venezuelan president Hugo Chávez — to the Lebanese militia group Hezbollah and the Islamic militant movement Hamas.

When discussing Latin America or any other issue, Bush can speak fluently in Spanish, which he began learning during a high school visit to Mexico, where he met his future wife, Columba.

“I would not be surprised if he wrote it totally on his own,” said former GOP congressman Lincoln Diaz-Balart, who introduced Bush to the crowd. “For years I have known Jeb to be constantly studying and thinking. He knows the world.”

Alice Crites and Anne Gearan contributed to this report.