WASHINGTON — When President Obama addresses the nation on Wednesday to explain his plan to defeat Islamic extremists in Iraq and Syria, it is a fair bet he will not call them the “JV team.”

Nor does he seem likely to describe Iraq as “sovereign, stable and self-reliant” with a “representative government.” And presumably he will not assert after more than a decade of conflict that “the tide of war is receding.”

As he seeks to rally Americans behind a new military campaign in the Middle East, Mr. Obama finds his own past statements coming back to haunt him. Time and again, he has expressed assessments of the world that in the harsh glare of hindsight look out of kilter with the changed reality he now confronts.

In making his speech, Mr. Obama faces the challenge of reconciling those views with the new mission he is presenting to the American public to recommit the armed forces of the United States to the region he tried to leave. Rather than a junior varsity nuisance, he will try to convince Americans that the Islamic State in Iraq and Syria represents a clear threat to national security in a state that is hardly stable. And he will seek to win patience for more war from a public that wishes it really was receding.