Offering sympathy but no easy answers, U.S. President Barack Obama came to Orlando, Fla., on Thursday to try to console those mourning the deadliest mass killing by a single shooter in U.S. history

Air Force One touched down around noon in this grief-stricken community, where Obama and Vice-President Joe Biden planned to spend a few hours meeting privately with families of the 49 victims, with survivors and with local law enforcement officials who responded to the shooting.

After the meeting with the families, Obama told reporters that if the U.S. does not act to control gun violence and homegrown terrorism, massacres like the one in Orlando will continue.

"If we don't act, we will keep seeing more massacres like this, because we will be choosing to allow them to happen," he said.

The president reiterated the need for gun law reforms, saying that while the motivation maybe have been different from what led to attacks in communities like Aurora, Col., and Newton, Conn., the instruments of death were similar, noting that those killed and injured were gunned down by a single individual with a powerful assault weapon.

Obama also said the families' grief is "beyond description," and that those killed "are part of the American family."

The low-profile visit reflected the challenge for the president to find something meaningful to say about an attack that has stoked a wide mix of fears about terrorism, guns and violence against gays.

Even as the families of the victims bury their loved ones, it's unclear what led a 29-year-old Muslim born in New York to open fire in a gay nightclub early Sunday where he may have been a frequent patron.

White House press secretary Josh Earnest said Obama would deal with the ambiguity about the shooting by focusing on the victims.

"The president's visit to Orlando has nothing to do with the individual who perpetrated this terrible attack," Earnest said Wednesday. He said Obama intended to tell residents "that they're not alone, even as they endure what surely have been several dark nights."

The White House released few details in advance about Obama's trip, which aides said was hurriedly arranged in a fraction of the time usually required to plan a presidential trip. But Obama planned to use the visit "to make clear that the country stands with the people of Orlando, stands with the LGBT community in Orlando, as they grieve for their loss," Earnest said.

Orlando Mayor Buddy Dyer, left, holds an 'Orlando United' shirt while greeting Barack Obama after the U.S. president arrived in the city. (Aul Loeb/AFP/Getty Images)

Vicious political brawl

The president's call for rejecting bigotry against gays and lesbians is complicated by the possibility that the gunman, Omar Mateen, may have been wrestling with his own sexuality. The FBI has been looking into reports that Mateen frequented the nightspot and reached out to men on gay dating apps.

Another challenge is to strike the appropriate tone at a time when the initial shock over the deadliest mass shooting in modern U.S. history has quickly given way to a vicious political brawl in Washington and on the campaign trail.

Since the shooting, presumptive Republican presidential nominee Donald Trump has expanded his call for temporarily barring foreign Muslims from entering the U.S., even though the attacker was an American, and insinuated that Obama sympathized with or even supported terrorists. In a rare bout of public anger, Obama denounced both Trump and the Republican leaders who are still supporting him. Many of those Republican leaders also denounced Trump's rhetoric.

Mourners grieve at a vigil for the victims of the shooting at the Pulse gay nightclub in Orlando, Fla., on Monday. (Jim Young/Reuters)

In Congress, the attack has spurred yet another bitter fight over gun control, exposing deep frustration among supporters of stricter gun laws that no level of mass casualty seems to be enough to force gun control opponents to reconsider. Democratic Senator Chris Murphy, whose state of Connecticut shouldered the killing of 20 children in Newtown in 2012, led a filibuster on Wednesday to try to force a vote, insisting he would stay on the Senate floor "until we get some signal, some sign that we can come together."

Murphy and other Democrats are pushing a change to let the government prohibit people suspected of being terrorists from buying guns. In an unexpected twist, Trump said he planned to meet with the National Rifle Association "about not allowing people on the terrorist watch list, or the no-fly list, to buy guns."

For Obama, the trip to Orlando is an unwelcome return to one of the most difficult roles a president must fulfil: comforting the nation at times when few words seem capable of providing much comfort. Obama has lamented the frequency with which he's had to perform that duty, calling his inability to enact stricter gun laws the biggest frustration of his presidency.