Afghan leader Ashraf Ghani faces the cold reality of the end of US military presence in Afghanistan Friday when he meets with President Joe Biden in the White House.

With his government under increasing threat from an emboldened Taliban insurgency, Ghani will be hoping for a significant commitment of US aid for his government, which will be without the on-the-ground support of US forces for the first time in nearly two decades.

But any hopes for a delay in America's exit from its longest war are likely to be snuffed.

Biden has ordered the departure of all US forces from Afghanistan by this year's 20th anniversary of the September 11 attacks that triggered the invasion, saying he believes that no more can be achieved.

The final pullout, announced in April, has moved fast and some speculate the exit of some 2,500 US troops and 16,000 civilian contractors could be mostly completed in July.

"This visit is first about our ongoing commitment and support to the Afghan people and to the Afghan National Defense and Security Forces," White House spokeswoman Karine Jean-Pierre said Thursday.

"The president will emphasize the need for unity, cohesion, and for the Afghan government to focus on key challenges Afghanistan faces."

- Deep uncertainty as Taliban gain -
Ghani and Abdullah Abdullah, who is in charge of stalled negotiations with the Taliban on a power-sharing deal, arrived in Washington on Thursday as the rebels continued to gain ground in the country, both physically and propaganda-wise.

The looming US exit has left the country in a deep state of uncertainty, with many worried about the return to power of extremists who applied a brutal version of Islam to the population when they ruled from 1996-2001.

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The Wall Street Journal reported that a new US intelligence report assesses that the Taliban could possibly capture Kabul within six months -- though other experts downplay that scenario, at least in the short-term.

Still, the situation is being compared to the US withdrawal from Vietnam in 1973. 

Two years later, the South Vietnamese government that Washington had backed and then abandoned fell to North Vietnamese troops.

- 'Enduring commitment' -
Still apparently hoping to slow the US pullout, Ghani and Abdullah met Thursday with members of Congress, many of whom criticize Biden's decision to leave -- even though the withdrawal actually began under his predecessor Donald Trump last year.

Senate Republican leader Mitch McConnell urged Biden to delay the withdrawal after talks with the Afghan leaders.

"President Biden's decision to withdraw US forces leaves our Afghan partners alone to confront threats that his own top advisors acknowledge are grave and growing worse," McConnell said.

On Friday, Ghani and Abdullah will meet with Biden in the White House and, separately, with Defense Secretary Lloyd Austin at the Pentagon.

"One of the things that we will certainly be talking with President Ghani about tomorrow is what the enduring commitment of the United States to his government is going to look like," said Pentagon spokesman John Kirby.

Biden is expected to reaffirm billions of dollars in US aid for the country, and possibly make arrangements for US civilian contractors -- essential to keep the Afghan air force flying -- to remain there.

The United States will also provide three million doses of Johnson & Johnson coronavirus vaccine to Afghanistan to be shipped as soon as next week, according to Jean-Pierre.

Andrew Watkins, an Afghanistan expert at the International Crisis Group, said Ghani wants to show he has US support as the country's leader.

"Ghani doesn't have a lot of domestic legitimacy. His legitimacy comes maybe more than from any other source or any other factor from international recognition and support," Watkins said.

The US side, meanwhile, is likely to pressure Ghani and Abdullah to strike a power-sharing deal with the Taliban sooner rather than later.

"We believe that a negotiated political settlement is the best way to end the conflict," Jean-Pierre told journalists. 

Possibly underscoring how uncomfortable the situation is for both sides, no press conference was planned.