• A senior State Department official overseeing the Biden administration's Haiti policy has resigned, citing what he calls the United States' "inhumane, counterproductive" response to the recent Haitian migrant surge along the Southern border. 
• The diplomat, Daniel Foote, was appointed U.S. Special Envoy to Haiti in late July by President Joe Biden, following the assassination of Haiti’s sitting president, Jovenel Moïse.
•  “Our policy approach to Haiti remains deeply flawed, and my recommendations have been ignored and dismissed,” Foote wrote in a scathing resignation letter on Wednesday that was obtained by NBC News.
• The State Department denies that Foote's proposals were ignored.
• Instead, department spokesman Ned Price said some of them were "rejected" because they were deemed "harmful" to promoting democracy in Haiti.

WASHINGTON -- A senior State Department official overseeing the Biden administration's Haiti policy has resigned, citing what he calls the United States' "inhumane, counterproductive" response to the recent Haitian migrant surge along the Southern border. 

The diplomat, Daniel Foote, was appointed U.S. Special Envoy to Haiti in late July by President Joe Biden, following the assassination of Haiti's sitting president, Jovenel Moïse. 

"Our policy approach to Haiti remains deeply flawed, and my recommendations have been ignored and dismissed," Foote wrote in a scathing resignation letter on Wednesday that was obtained by NBC News. 

The State Department denies that Foote's proposals were ignored. Instead, department spokesman Ned Price said some of them were "rejected" because they were deemed "harmful" to promoting democracy in Haiti.

Foote wrote that his decision to resign now was in response to the decision by U.S. immigration authorities to deport thousands of Haitian migrants back to Haiti.

"The people of Haiti, mired in poverty, hostage to the terror, kidnappings, robberies and massacres of armed gangs and suffering under a corrupt government with gang alliances, simply cannot support the forced infusion of thousands of returned migrants lacking food, shelter, and money without additional, avoidable human tragedy," Foote wrote.

However, Price accused Foote of having "failed to take advantage of ample opportunity to raise concerns about migration during his tenure and chose to resign instead."

Since mid-September, more than 10,000 Haitian migrants have attempted to cross the Rio Grande river and enter the U.S. from Mexico near the tiny Texas town of Del Rio. The result has been a dual humanitarian and border crisis, with thousands of migrants amassing under a bridge with no food, water or shelter. 

In response, U.S. border patrol agents have detained thousands of people. While families with children have largely been permitted to apply for asylum, 1,401 people have been flown back to Haiti since Sunday, when deportation flights began, White House press secretary Jen Psaki said Thursday.

Less than 5,000 migrants remained at the Del Rio bridge location on Thursday, said Psaki.

The surge was triggered by several convergent factors, including the collapse of Haiti's government in July, an earthquake in August that killed more than 2,000 people and a mistaken belief that the Biden administration would grant asylum and protected status to newly arrived Haitian migrants. 

"The collapsed state is unable to provide security or basic services, and more refugees will fuel further desperation and crime," Foote wrote. 

Foote's resignation is the latest blow to the Biden administration, which has struggled to deal with the flood of Haitian migrants. 

Many of the migrants have not lived in Haiti for years, having fled the country to look for work in South America following Haiti's devastating 2010 earthquake. 

The fact that they did not recently live in Haiti significantly complicates the legal question of whether they would qualify as refugees fleeing the current unrest in Haiti, as well as the ethical question of whether to deport them back to a country many of them have not seen in years.

In Washington, President Joe Biden has come under sharp criticism from refugee organizations and key Democrats in Congress for his administration's response to this latest border crisis.

They accuse the White House of leaning on a controversial Trump-era Covid-19 public health rule known as Title 42, that allows immigration authorities to immediately remove most undocumented border crossers without first giving them a chance to apply for asylum. 

On Tuesday, Senate Majority Leader Chuck Schumer pressed Biden and Homeland Security Secretary Alejandro Mayorkas to "immediately put a stop to these expulsions and to end this Title 42 policy at our southern border."

"We cannot continue these hateful and xenophobic Trump policies that disregard our refugee laws," Schumer added.

--- CNBC's Kevin Breuninger contributed reporting to this story.