Republican presidential candidate Jeb Bush will vow on Tuesday to pursue an aggressive strategy against Islamic State militants if elected, in a speech on foreign policy in which he will also seek to blame Democrat Hillary Clinton for some of the unrest in Iraq.
Bush is to deliver a 9pm EDT (2300 GMT) speech at the Ronald Reagan presidential library in Simi Valley, California, where the next debate will take place on September 16 among candidates for the 2016 Republican presidential nomination.
Excerpts of the speech released by his campaign show that Bush will call Islamic State "the focus of evil in the world today" and say that, if elected in November 2016, he would embark on an "unyielding" effort to overcome the threat.
"We should pursue the clear and unequivocal objective of throwing back the barbarians of ISIS, and helping the millions in the region who want to live in peace," Bush will say. ISIS is another name for the Islamic State group.
He will argue that President Barack Obama's policy, which relies heavily on air strikes against Islamic State targets in Syria and Iraq, is failing to turn the tide.
"Instead of simply reacting to each new move the terrorists choose to make, we will use every advantage we have, to take the offensive, to keep it, and to prevail," Bush will say. "In all of this, the United States must engage with friends and allies, and lead again in that vital region."
It is a delicate subject for Bush since his brother, former President George W Bush, started a war in Iraq in 2003 based on allegations that Iraqi President Saddam Hussein possessed weapons of mass destruction that were never found.
Jeb Bush will say Obama's insistence on not leaving a US contingency force behind in Iraq, after the success of the Bush-led troop surge late in his presidency, created a security vacuum that left the region open to the growth of Islamic State.
He will say Clinton, who was Obama's first-term secretary of state, deserves some of the blame. Clinton's foreign policy experience is a major selling point for her candidacy.
"Where was secretary of state Clinton in all of this? Like the president himself, she had opposed the surge, then joined in claiming credit for its success, then stood by as that hard-won victory by American and allied forces was thrown away," Bush will say.
"In all her record-setting travels, she stopped by Iraq exactly once," he will say.