WASHINGTON (AP) — The deadly shooting spree in Colorado consumed the U.S. presidential campaign Friday, sidetracking a bitter political contest with a tragedy that at least temporarily brought the candidates together in common purpose.

“There are going to be other days for politics,” a somber President Barack Obama said.

Obama and Republican challenger Mitt Romney altered their campaign schedules to address the killings. Both issued statements of condolences, calling for prayer and unity in the aftermath of the overnight bloodshed at a suburban Denver movie theater.

In Florida for a campaign swing, Obama asked for a moment of silence and focused his shortened remarks exclusively on the tragedy. The president said the shooting was a reminder that life is fragile, and added that the event “reminds us of all the ways that we are united as one American family.”

He said Friday should be devoted to prayer and reflection. He then canceled a later appearance and was returning to Washington ahead of schedule.

The issue of gun control is deeply felt in the United States, but had not really surfaced in any significant way during the presidential campaign.

Republicans have accused Obama of trying to erode gun owners’ rights, yet — despite promising to limit access to firearms during the 2008 campaign — the president has said and done little about guns since he was elected, deeply disappointing gun-control groups. In its most recent assessment, in 2010, the Brady Center to Prevent Gun Violence flunked on Obama on all seven issues it deemed important.

“As someone who has suffered the lasting impact of gun violence, and president of Brady, I can tell you that we don’t want sympathy. We want action,” Dan Gross, president of the Brady Campaign to Prevent Gun Violence, said in a statement Friday.

Gun rights groups are a powerful lobby in the U.S. where to many people, especially in the more conservative and rural areas, easy access to guns is a way of life. Reasons for that go as far back as the western frontier culture of the 19th century and before — the right to bear arms is guaranteed by the U.S. Constitution, alongside such basic rights as free speech and freedom of religion.

New York Mayor Michael Bloomberg is among officials wanting stricter gun control. In a radio interview, he admonished both the president and his challenger to forcefully address gun violence.

“You know, soothing words are nice, but maybe it’s time that the two people who want to be president of the United States stand up and tell us what they are going to do about it, because this is obviously a problem across the country,” he said.

Obama and Romney both moved Friday to pull down negative campaign advertising.

Romney was scheduled to comment on the shooting during his own campaign appearance in New Hampshire and canceled some media interviews.

Romney, in a written statement, said: “We are praying for the families and loved ones of the victims during this time of deep shock and immense grief. We expect that the person responsible for this terrible crime will be quickly brought to justice.”

Obama sought to temper the campaign spirit. He thanked his supporters and said he had looked forward to talking about the differences between Romney and him, saying instead: “This, I think, is a day for prayer and reflection.”

Nevertheless, his supporters added a political touch by chanting “Four more years!”