President Obama pauses while speaking to reporters in the Oval Office on Monday after being briefed on the investigation of the nightclub shooting in Orlando. (AP Photo/Pablo Martinez Monsivais) (Pablo Martinez Monsivais/AP)

This was supposed to be the week President Obama jumped fully and gleefully into the 2016 campaign at a triumphant joint rally with Hillary Clinton that would highlight how far his Demo­cratic administration has brought the nation over seven-plus years in office.

Instead, the Orlando massacre quickly resurrected the debate over one of the president’s greatest areas of political weakness and personal frustration. The worst mass shooting in U.S. history Sunday thrust Obama on the defensive over terrorism and gun control just as he had begun to try to frame the stakes of the November election. The White House announced late Monday that Obama would travel to Orlando on Thursday to pay tribute to the victims.

In place of an image of Democratic unity, with Obama and Clinton, the presumptive presidential nominee, on stage together in Green Bay, Wis. — where Clinton canceled the rally planned for Wednesday — reporters spent much of Monday parsing Clinton’s reaction to the shooting for signs that she had split from the president on his national security policies.

Specifically, Clinton told CNN she is not afraid to use the phrase “radical Islamism,” which Obama has refused to use in describing terrorist attacks, although the former secretary of state did not fault the president.

“I feel confident in telling you that, having worked in this administration for four years, she is somebody who agrees strongly with the president’s approach,” White House press secretary Josh Earnest told reporters during his daily briefing.

FBI Director James B. Comey listens to President Obama speak to members of the media at the White House on Monday. (Pablo Martinez Monsivais/AP)

The slaying of 49 people in a gay nightclub by a gunman marked another in a long list of high-profile mass shootings that has punctuated Obama’s tenure. But the timing, scale and circumstances of the Orlando massacre highlighted the political risk for the president as he seeks to calm public fears and reassure the public that his administration is exhausting all avenues to keep Americans safe.

Obama’s fiercest critics, including presumptive Republican nominee Donald Trump, wasted little time attacking the president, calling him soft on terrorism and lambasting him for his refusal to define the killings as the work of radical Islam. Trump also called for a ban on Middle Eastern immigrants to the United States.

Even as the president defended his approach to combating violent extremism, his efforts to highlight the role of lenient U.S. gun regulations in aiding the Orlando shooter in maximizing the carnage served to call attention to the Obama administration’s inability to take stronger actions to change the law. The president has called the failure to push gun control reforms through Congress after the December 2012 shooting deaths of 20 elementary school students in Newtown, Conn., the most stinging legislative defeat of his presidency.

Speaking to reporters in the Oval Office, Obama emphasized that the gunman, Omar Mateen, appeared to be a self-
radicalized actor with sympathy for the Islamic State militant group but with no direct ties to that or any other terrorist network.

Obama cautioned the public not to retreat to partisan corners in the aftermath of the attack, suggesting that the solution to extremist violence should not be considered in reductive terms based on political ideologies.

“My concern,” Obama said, “is that we start getting into a debate, as has happened in the past, which is an either/or debate, and the suggestion is either we think about something as terrorism and we ignore the problems with easy access to firearms. Or it’s all about firearms and we ignore the role, the very real role, that organizations like [the Islamic State] have in generating extremist views inside this country. It’s not an either/or. It’s a both/and.”

While Obama’s overall job approval ratings have topped 50 percent in his final year in office, the public has remained uneasy about his counterterrorism strategies.

Since the rise of the Islamic State in Syria and Iraq in 2014, less than half the public has approved of the way Obama has been “handling the threat of terror,” according to a series of Washington Post-ABC News polls. The figure stood at 43 percent in December in the wake of a mass shooting in San Bernardino, Calif., by a married couple purportedly inspired by the Islamic State. By contrast, the figure was 69 percent after he ordered the U.S. military raid that killed Osama bin Laden in 2011.

Despite public skepticism, the president has refused to alter his approach, and he has sought to place the mass shootings into context, suggesting that Americans should be vigilant but not fearful at home. After past incidents, Obama has followed through on pre-planned trips outside Washington in an effort to project confidence and show that his administration would not be cowed by the violent acts of extremists.

But the outsize political impact of the Orlando attacks was evident Monday at the White House, where the president met with an expanded cast of top advisers during his daily national security briefing. Obama aides were debating privately whether to alter more of his public schedule, which includes a congressional picnic Tuesday and a three-day trip to national parks in New Mexico and California, starting Friday.

“My hope is that over the next days and weeks that we are being sober about how we approach this problem,” Obama said, “that we let the facts get determined by our investigators, but we also do some reflection in terms of how we can best tackle what is going to be a very challenging problem, not just here in this country but around the world.”

On Tuesday, Obama will hold a long-scheduled meeting with his National Security Council at the Treasury Department, the latest in a rotating series of meetings at various federal agencies that the president initiated after the Paris attacks to show the public he is focused on the fight against terrorism. Last week, the administration’s top coordinator for the strategy against the Islamic State briefed reporters at the White House on progress that has been made in the Middle East.

But for Obama and Clinton, the Orlando massacre offers another tricky test of their ability to coordinate their messages on the campaign trail.

Clinton expressed some mild disagreements with Obama’s Syria strategy in her 2014 autobiography, “Hard Choices.”

Since then, she has largely tied herself to her former boss. In an endorsement video last week, Obama returned the favor.

“I don’t think there’s ever been someone so qualified to hold this office,” the president said. “From the decision we made in the Situation Room to get bin Laden, and our pursuit of diplomacy in capitals around the world, I have seen her judgment. I have seen her toughness.”

Whether Clinton so forcefully echoes those sentiments about him in the coming days remains to be seen.

Scott Clement contributed to this report.