In Wake of Colorado Tragedy, a Concern Over the Propriety of Campaigning Mr. Obama woke on Friday morning and was told about the shootings by his homeland security adviser, John O. Brennan, at 5:26 a.m. Within an hour and a half, the president had released a written statement calling for national unity. "As we do when confronted by moments of darkness and challenge, we must now come together as one American family," he said. His advisers, meanwhile, discussed whether he could go forward with a day of campaigning as scheduled and if so how he should adjust his speeches. The president was slated to address political rallies here and in Orlando on the final day of a two-day swing through this critical battleground state. The Obama team decided to go ahead with the first speech here and a spokeswoman, Jen Psaki, said he would address the tragedy "in shortened remarks." But the president decided to cancel the second rally and return early to Washington. The real-time reaction of the campaign proved that it is hard to go from calling for the American family to come together one moment to putting on a partisan hat and swinging away at an opponent the next. Mr. Romney, campaigning in New Hampshire, decided to go ahead with a campaign event in the town of Bow but planned to address the shooting in his remarks. In advance of the lunchtime event, he released a written statement in the early hours much like the president's. "We are praying for the families and loved ones of the victims during this time of deep shock and immense grief," he said. The challenge of how to handle such a moment, of course, is more acute for Mr. Obama, who besides being the putative Democratic nominee is actually leader of all Americans with a duty that transcends that of Mr. Romney at this point. While there is no continuing threat required to be managed from the White House, it falls to a president at times like these to not only pull the country together in its grief but to try to explain and make sense of something so senseless. That was something both Presidents Bill Clinton and George W. Bush excelled at during tragedies like the Oklahoma City bombing and the attacks of September 11. Both presidents, in fact, were defined by their responses to those events, which were often seen as their best moments in office. That sort of scenario has not been Mr. Obama's particular strength. While he is a master orator who can stir a stadium of 80,000 people with soaring words of national purpose, he is also a man of natural reserve who has not always connected as intimately with audiences during national grief. Still, he has been more effective at speeches about unity and the tragedy in Colorado may tie into his recent we're-in-this-together theme. As it happened, Mr. Obama had already planned to use Friday's speeches to talk about that. Hammered in recent days by Mr. Romney for saying that businesses are not built by business owners alone, that they rely on a society that provides education, roads and businesses, Mr. Obama had scripted a response to explain what he meant. Of course, the president had intended to use it as a counterpunch against Mr. Romney. Whether he follows through on that in light of events, and if so can he do it without appearing unseemly, could be a telling moment.