The US diplomat leading talks with the Taliban was due to appear in Washington on Friday to discuss an ongoing push for a political settlement to the 17-year-old Afghanistan conflict.
Zalmay Khalilzad, a former US ambassador to Afghanistan who is now special envoy in the talks, has in recent months held meetings with Taliban officials in Qatar.
Khalilzad was scheduled to speak at the US Institute of Peace at 2:00 pm (1900 GMT).
He has expressed cautious optimism about the prospect of a deal, and even announced a draft framework, but stressed nothing had been finalized.
Critics are skeptical about the talks for a number of reasons, primarily because they have not yet included the Afghan government, which the Taliban considers US-backed puppets.
Additionally, the Taliban have promised not to provide shelter again to foreign extremists, but experts say they cannot be trusted and even now are helping to hide foreign militants.
The talks come as President Donald Trump pushes to end the Afghanistan conflict, where about 14,000 US troops are still deployed and which has seen countless thousands of civilian and military deaths, as well as an infusion of more than $1 trillion in US cash into the country.
In his annual State of the Union speech on Tuesday, Trump said the time has come "to at least try for peace."
Afghanistan has suffered nearly constant conflict since the Soviet invasion of 1979, which was followed by civil war, the Taliban regime, and the US invasion in late 2001.
Khalilzad was a major player in George W. Bush's administration when the United States first invaded Afghanistan after the September 11, 2001 attacks.