WASHINGTON  — President Barack Obama’s escalating military campaign in Iraq and Syria has drowned out the economic pitch he hoped would help salvage a midterm election that has been favoring Republicans. But the airstrikes against Islamic State extremists have also introduced a new complicating factor into the fall campaign, forcing both sides to reassess their closing political messages.

Obama is drawing new attention to the nation’s recovery from the Great Recession with a speech Thursday at Northwestern University, linking U.S. stature abroad to economic strength at home. It is a delicate argument for a president whose handling of pocketbook issues remains unpopular and who acknowledges many have not benefited from the upturn.

Senior administration officials insist that unlike George W. Bush in 2002, Obama does not plan to make national security and the threat of Middle East extremism the centerpiece of his message for the homestretch of the fall campaign. Yet they acknowledge the matter will be impossible for Obama and Democrats to ignore.

“You’d like to be able to be talking about the economy in September, but this is a really important piece of business for the president of the United States to do,” said Jennifer Palmieri, the White House communications director. “I don’t think it’s time lost.”

Republicans, too, have had to confront the new dynamic posed by the airstrikes.