President Joe Biden has offered comfort to the grieving and federal support for efforts to search for the missing and rebuild after the collapse of a high-rise building on the Florida coastline.

Mr Biden, responding to what appeared to be the deadliest calamity of his young presidency, was to survey the devastation and meet first responders hunting for survivors among the rubble in Surfside.

But underscoring the dangers still present, work was halted before Mr Biden arrived due to concerns about the stability of the section still standing.

Mr Biden and his wife Jill arrived in Florida a week after the collapse of the 12-storey Champlain Towers South beachfront condominium killed at least 18 people and left 145 missing.

Hundreds of first responders and search-and-rescue personnel have been painstakingly searching the rubble for potential signs of life. No one has been rescued since the first hours after the collapse.

“This is life and death,” Mr Biden said at a briefing about the collapse. “We can do it, just the simple act of everyone doing what needs to be done, makes a difference.”

The president said he believed the federal government has “the power to pick up 100% of the cost” of the search and clean-up and urged local officials to turn to Washington for assistance.

“You all know it, because a lot of you have been through it as well,” Mr Biden said. “There’s gonna be a lot of pain and anxiety and suffering and even the need for psychological help in the days and months that follow. And so, we’re not going anywhere.”

Mr Biden was briefed on the situation with Florida Governor Ron DeSantis and Miami-Dade County Mayor Daniella Levine Cava.

The mayor saluted the efforts to cross party lines in a time of “an unprecedented devastating disaster” and added that the unified government and community response “is what gives us hope”.

Mr DeSantis, a rumoured Republican 2024 presidential candidate, said to Mr Biden that the “cooperation has been great,” declaring that the administration has “not only been supportive at the federal level, but we’ve had no bureaucracy”.

As Mr Biden pledged federal help, he touched Mr DeSantis’s hand to underscore the point.

Later, the president was expected to meet first responders who have worked around the clock on a rescue effort that has stretched into its second week amid oppressive heat and humidity and frequent summer storms.

He was also expected to meet for several hours with family members of those affected by the collapse before delivering remarks on Thursday afternoon.

White House spokeswoman Karine Jean-Pierre said Mr Biden aimed to “offer up comfort and show unity” with his visit to the site.

Few public figures connect as powerfully on grief as Mr Biden, who lost his first wife and baby daughter in a car crash and later an adult son to brain cancer.

In the first months of his term, he has drawn on that empathy to console those who have lost loved ones, including the more than 600,000 who have died in the Covid-19 pandemic.