But the president’s emphasis on those who hope to follow him into the White House was revealing. As he enters the last six months of his term, Mr. Obama has been talking to his advisers about the burdens his successor will bear in consoling bereaved families and settling the nerves of the nation after another mass shooting. If Americans cannot find a way to stop this cycle of violence — and Mr. Obama predicted on Sunday that there would be another killer who would seek to divide people — the next president will have to double as a national grief counselor.

With the Republican and Democratic conventions likely to dominate news coverage for the next two weeks, Mr. Obama also recognizes that the power of his words is diminishing. For months now, he has seen how the campaign has stirred up such vitriolic anti-Washington sentiment that it has all but drowned out his appeal for coolheaded debate or common-sense solutions.

“It makes it extremely difficult for him to change minds or compel action, however rational that action may seem,” said Robert Dallek, the historian who has written books about Franklin D. Roosevelt, John F. Kennedy, Lyndon B. Johnson and Ronald Reagan. “The distractions of the current political campaign, at some level, make his words superfluous.”

Superfluous, perhaps, but still necessary: Mr. Obama has spoken more than a dozen times after mass shootings. On Sunday, after the ambush of police officers in Baton Rouge, the White House issued a statement from the president. A few hours later, it notified the news media that he would appear in the briefing room at 4:30 p.m., soon after the governor of Louisiana and other state and local officials spoke to reporters in Baton Rouge.

For Mr. Obama, it was the seventh time in 10 days that he had appeared before cameras after an outbreak of violence. The string of shootings had in fact consumed most of his time. The president spent part of a flight to Europe fine-tuning his remarks in response to a pair of earlier shootings, in Baton Rouge and Minnesota, before speaking to reporters after landing in Warsaw. The next morning, he spoke again after the shootings in Dallas, and then a third time at the end of a NATO summit meeting.