The family of missing April Jones has launched a pink ribbon campaign - as police are granted more time to question the main suspect.
People are being urged to fix a pink ribbon to their front doors or gates, or to a wear a pink ribbon, as the hunt for the youngster intensified.
The five-year-old's godmother Mair Raftree said pink was April's favourite colour.
The campaign was launched as police were given permission by magistrates to extend questioning of suspect Mark Bridger.
Prime Minister David Cameron joined police in urging anyone with any information at all about the whereabouts of the "lovely girl" to speak to officers.
A news conference will be held at 11am and is expected to reveal more details of the investigation, Dyfed Powys police have confirmed.
Meanwhile, rain hampered the search for the youngster this morning.
The mayor of Machynlleth, Gareth Jones, said bad weather in Wales was making it more difficult for rescuers, focusing on 20 sites in the area.
April vanished near her home in the Bryn Y Gog estate in Machynlleth, mid Wales, at around 7pm on Monday.
It has emerged that April has cerebral palsy and other health problems and will be desperately needing her medication.
Ms Raftree, 41, said: "This is the third day April is away from her home and she is only little. She needs medication for her health problems and without it she will be in pain.
"She has been in hospital a few times for her condition and with the cerebral palsy her legs just give way. I am so scared for her and I desperately want her home."
Ms Raftree, a childminder from Aberystwyth, said April has also spent time in hospital because of her irritable bowel syndrome (IBS).
The girl needs to take a regular dose of painkillers for the stomach disorder.
Ms Raftree told Sky News' Kay Burley that April's mother Coral was doing her best to cope under the circumstances.
Mr Bridger, 46, was arrested by officers on Tuesday and has been interviewed on at least two occasions.
He was picked up by officers while on foot - with police later confirming he was wearing camouflage-style clothing.
His blue L Reg Land Rover had been retrieved from a repair garage in Machynlleth.
Police are appealing for anyone who saw the former soldier or his car, registration number L503 MEP, to come forward.
Detective Superintendent Reg Bevan said officers had received more than 400 messages from the public since their earlier appeal to find her.
Overnight, specialist teams continued to search areas around the Dyfi River.
Chris Lloyd from the Ogwen Valley Mountain Rescue Association told Sky News: "It's quite difficult working at night but it has its advantages.
"You don't have a glare on the top of the river. You can actually shine torches through the water."
He added: "The water level is falling but there are some places we haven't been able to search because of the intensity of the flow."
The team's search took them yards below a cottage in the hamlet of Ceinws which was being rented by Mr Bridger.
The 20 search scenes include houses, outbuildings, countryside and riverbanks around Machynlleth.
Officers are using a hovercraft to search marshland near the estuary.
Superintendent Ian John said the hunt was "continuing to grow and grow at quite a pace" and included officers from across the UK.
Some 100 mountain rescue volunteers, 100 police-trained search officers, 20 dog handlers, two boats from the RNLI, a team of kayakers, and the force's marine unit are taking part in the operation, he added.
He described it as an "unprecedented search in the UK".
Sky's Adele Robinson said sniffer dogs would be sailed along the river - zig zagging - searching for clues and April's scent.
Earlier, April's mother made an emotional appeal for help in finding her daughter.
Coral Jones, who was accompanied by her stepfather Dai Smith, sobbed as she said: "It's been 36 hours since April was taken from us.
"There must be someone out there who knows where she is and can help the police find her.
"We are desperate for any news. April is only five years old. Please, please, help find her."
After her plea, she broke down in tears, holding her head in her hands, and was comforted by Mr Smith as Det Supt Bevan made a further appeal for information.
He said: "We are pursuing a number of lines of inquiry and Mark Bridger is one of them.
"Do not assume somebody else has already contacted us with information. Even if you feel yours is trivial, it may be the vital piece that we are missing."
Meanwhile, the suspect's son Scott Williams told Sky News of his shock at hearing his father had been arrested.
The 19-year-old said his father had little to do with him or his mother Julie, but added he had "never done anything to anyone".
Anyone with information relating to the case is asked to call Child Rescue Alert Line on 0300 2000 333.