"Whatever you need from Washington, we are there", Trump told state and local officials at a briefing.
Even though Florence was downgraded into a tropical depression, officials say conditions are still unsafe.
Jordan is donating $1 million each to the American Red Cross and Foundation For The Carolinas' Hurricane Florence Response Fund.
The slow-moving storm has since been downgraded to a tropical depression and moved into the USA northeast.
Poultry producer Sanderson Farms says out their 880 broiler houses in North Carolina, 60 have flooded due to the hurricane.
The latest victims were two women in SC who drowned on Tuesday when a sheriff's department van in which they were riding was swept away by floodwaters.
Sampling waterways in eastern North Carolina after Hurricane Matthew showed a temporary increase in concentrations of some bacteria and pollutants in spots, according to a 2017 report from the state's Department of Environmental Quality.
Florence had effectively washed out normal contours of life across North Carolina, with Cooper saying that more than 1,100 roads were closed Tuesday and more than 340,000 people lacked power. Rivers swollen by days of rain still threaten communities barely touched by the storm.
At Fayetteville, about 161 kilometres inland, near the army's sprawling Fort Bragg, the Cape Fear River had risen about 15 meters toward a crest that was predicted to be more than seven metres above flood level. That has disrupted efforts to restore power, clear roads, and allow evacuated residents to go home.
Wilmington, just down the coast, remained nearly completely cut off by flooding from the Cape Fear River and earlier storm surges.
The governor said 16 rivers statewide were at major flood stage and more than 1100 roads were closed.
Kinston Police in North Carolina also posted a video on Facebook showing clumps of fire ants in flood waters, warning residents to stay safe.
North Carolina is the country's No. 2 swine-producing state, its leading producer of tobacco and a major poultry producer, making agriculture its principle industry, valued at $87 billion.
Environmental damage was also mounting as human and animal waste was swept up in roiling floodwaters.
Chicken farm buildings are inundated with floodwater from Hurricane Florence near Trenton, N.C., Sunday, Sept. 16, 2018.
The state's vast hog farms and their waste lagoons - which one environmentalist called "cesspools the size of football fields" - pose one of the greatest perils.
Florence is now a large low-pressure system and rainstorm moving across New England and into the Canadian Maritime provinces, but not before making itself felt in the mid-Atlantic with soaking rains and flash floods.
On Wednesday, the president is scheduled to depart the White House en route to Marine Corps Air Station Cherry Point in Havelock, North Carolina.
He visited a church in New Bern, a town of 30,000 people at the confluence of the Neuse and Trent rivers that was hit especially hard by flooding, and joined volunteers in passing out boxed meals to people in a drive-through line.