The proposal emerged as WFP executive director Ertharin Cousin was in Nigeria on a week-long trip to see programmes set up to stave off starvation.
Foreign Policy magazine reported on Thursday it had seen an executive order from President Donald Trump's administration that proposed cuts of 40 percent in voluntary US funding for UN agencies, including the WFP and Unicef.
The proposal emerged as WFP executive director Ertharin Cousin was in Nigeria on a week-long trip to see programmes set up to stave off starvation caused by Boko Haram's Islamist insurgency.
The UN children's fund Unicef is also present in the remote region, where the conflict has left at least 20,000 people dead and made more than 2.6 million others homeless since 2009.
Asked about continued US support for WFP activities in Nigeria and around the world, Cousin told AFP late on Thursday: "The US has been the largest donor to WFP for over 50 years.
"Our hope is that this organisation, which serves humanity around the globe and ensures that children don't go hungry, that has benefitted from support on the Republican as well as the Democratic side of the house, can continue to depend upon receiving the financial assistance that's necessary."
A cut by Washington would mean a cut in "lifesaving support", she added.
Northeast Nigeria has seen an influx of international non-governmental organisations in recent months because of high incidences of acute malnutrition, particularly among children under five, and reports of famine in some hard-to-reach areas.
Security has improved across the ravaged states of Borno, Yobe and Adamawa, allowing aid agencies to reach hundreds of thousands of people who have lost their homes and livelihoods, including farmland.
The WFP said it helped just over one million people in December with high nutrition supplements and "in kind" monthly cash transfers to buy food. It aims to reach 1.8 million in the first quarter of this year.
Funding is a major issue for NGOs tackling the fallout from the Boko Haram conflict, which has devastated an already poverty stricken region and spread to neighbouring Cameroon, Chad and Niger.
The WFP says it currently has a shortfall of $173 million (162 million euros) to fund its programmes in northeast Nigeria.
Cousin said despite repeated appeals for urgent funding last year, "not enough people are aware" of the conflict and its effect on the civilian population.
"We need to ensure that we raise the profile of the challenges... faced by the 4.4 million people here who are food insecure and the 1.8 million people who are severely food insecure," she added.
"Our funds will run out in mid-March but we're hopeful that it won't take babies beginning to die before the world pays attention."
Violence by the Islamic State group affiliate has left schools, health centres, government buildings and telecoms infrastructure destroyed along with farmland.
At the same time, shortages and spiraling inflation nudging 20 percent have pushed up prices in markets, making food unaffordable for many of those who have fled.
Ayoade Alakija, the Nigerian government's chief humanitarian coordinator, said any cut in US funds would have a global impact on child and maternal health projects.
"It's going to be catastrophic. We are our brother's keeper. We have a common shared humanity and that's what global leadership really means -- and he (Trump) doesn't get that," she said.
"The consequences of ignoring responsibility" were huge, she added.
Nigeria's government has accused aid agencies of exaggerating the scale of the humanitarian crisis.
But WFP regional director for West Africa Abdou Dieng said the authorities now realised the scale of the problem and there was better coordination between everyone involved, though challenges remained, particularly regarding security.
"We've reached a kind of cruising speed now and we think we will be able to continue in this direction and for that we need a huge amount of resources," he said in an interview at the WFP office in Maiduguri.
Dieng warned that aid agencies could be hit by a planned six-week closure from early March of the airport in the capital Abuja, whence most aid -- and humanitarian workers -- are flown to the northeast.
"We're looking at possibilities that exist. If it (the closure) is limited to six weeks there'll be an impact but if it's over that the impact will be a lot bigger," he added.