TORONTO -- U.S. President Donald Trump will make a "major statement" Sunday morning, but the White House remains tight-lipped about what the president will discuss in the unusual last-minute announcement.

Trump teased the event late Saturday night in a cryptic tweet.

“Something very big has just happened!” Trump tweeted.

Trump will make the announcement at 9 a.m. at the White House, spokesman Hogan Gidley confirmed following the tweet.

In recent weeks, Trump has faced mounting pressure amid the impeachment inquiry and questions about why he pulled U.S. troops out of Syria.

On Saturday, Democrats met for a rare weekend sitting as the impeachment inquiry moved ahead full force.

The impeachment inquiry is tied to a July 25 phone call that Trump made to Ukrainian President Volodymyr Zelenskiy in which Trump asked the Ukranian leader to pursue investigations into his political foe and Democratic presidential candidate Joe Biden.

Trump has called the impeachment inquiry a “sham” and repeatedly said he never offered Ukraine anything in return for the investigations he sought. However, witness testimony has contradicted that claim.

With files from The Associated Press