NEWPORT, R.I. — If the world seems troubled by all manner of calamities these days, President Obama does not want Americans to worry too much. After all, he said Friday, “The world has always been messy”; it is just more apparent because of social media. And, he added, today’s geopolitical threats are far less perilous than those of the Cold War.

Governing at a time of war, terrorism and disease, and frustrated on multiple fronts at once, Mr. Obama finds himself trying to buck up supporters heading into a crucial midterm election season. The succession of international crises has taken a toll on the public mood, not to mention his own poll ratings, and he seems intent on reassuring Americans that the challenges are manageable.

As he spent Friday sweeping through New York and Rhode Island to raise hundreds of thousands of dollars for vulnerable Democrats, Mr. Obama addressed that public apprehension directly, acknowledging that many Americans “are feeling anxious” about their country and its place in the world. The showdown with Russia over Ukraine, the emergence of a radical new Islamic caliphate in Syria and Iraq, and the rise of China have stirred unease about the future of the United States, he said.

“If you watch the nightly news, it feels like the world is falling apart,” he said at a Democratic fund-raiser in Purchase, N.Y., just north of New York City. Expanding on a theme he has touched on at recent fund-raisers, Mr. Obama agreed that “we are living through some extraordinarily challenging times” and “I can see why a lot of folks are troubled.”