By Michael Hernandez

WASHINGTON

Concern is reportedly mounting within the Trump administration over President Donald Trump's interest in a proposal to privatize the war in Afghanistan.

Trump unveiled last year a new effort to gain ground against the Taliban and bring the group to the negotiating table. But the renewed effort has failed to secure the advances Trump sought, and he has been increasingly frustrated over the lack of progress in the U.S.-led campaign.

The quagmire has renewed his interest in a proposal by the former head of the controversial Blackwater private military group to largely swap out U.S. troops in the country with contractors. The private contractors would report to a government envoy who would, in turn, report to Trump, according to NBC News.

The plan by Erik Prince, the former Blackwater CEO, was first floated last year when Trump was mulling a new Afghanistan strategy. But it has been vociferously opposed by the president's closest aides.

A video recently shot by Prince has renewed Trump's interest, an anonymous senior administration said, according to NBC. In the video Prince argues the U.S. could save money - one of Trump's must publicly reiterated promises - by adopting the proposal.

A National Security Council spokeswoman said, however, that "no such proposal from Erik Prince is under consideration."

"The President adopted the South Asia strategy after months of deliberation among his key national security advisors," the spokeswoman, who discussed the matter publicly, said in a statement to Anadolu Agency.

"The President, like most Americans, would like to see more progress in Afghanistan. However, he also recognizes that withdrawing precipitously from Afghanistan would lead to the re-emergence of terrorist safe havens, putting American national security and lives in danger," she added.

In an interview with NBC News, Prince said Trump's advisers are drawing "as rosy a picture as they can" about the situation in Afghanistan, and "over-emphasize the fluff and flare of these so-called peace talks."

"I know he's frustrated," Prince said of Trump. "He gave the Pentagon what they wanted... And they haven't delivered."

The U.S. has been fighting in Afghanistan since it invaded in 2001, shortly after the September 11 terrorist attacks of that year.

The war in Afghanistan is the U.S.'s longest-running conflict.