WASHINGTON (AP) — President Donald Trump still won't bring himself to concede the election he decisively lost to President-elect Joe Biden. But he's now acknowledging he will leave the White House if Biden's win is affirmed by the Electoral College, which is firmly on track to do just that in a few weeks.

"Certainly I will," he said Thursday when asked if he will vacate the premises after electors make Biden's win formal. "But you know that."

Trump, who took questions from reporters for the first time since the election, unleashed another round of complaints about the vote and theatrical warnings that "a lot of things" would happen before the Electoral College meets Dec. 14 that could possibly change results. But while he's stirring uncertainty about how he will behave in the weeks ahead, there is no real suspense about the outcome.

All states must certify their results before the Electoral College meets and any challenge must be resolved by Dec. 8. States have already begun that process, including Michigan, where Trump and his allies tried and failed to delay the process, and Georgia and Pennsylvania.

Nothing stands in the way of Biden taking office Jan. 20 with a clear margin of electoral votes.

No concession is needed from Trump for Biden to become president, none has been offered and Trump may never admit he was beaten fair and square. But there were a few signs that Trump was coming to terms with his loss.

At one point he expressed concern that Biden would get the glory from pending coronavirus vaccines. "Don't let him take credit for the vaccines," Trump said, "because the vaccines were me, and I pushed people harder than they've ever been pushed before."

The fact that a sitting American president even had to address whether or not he would leave office after losing reelection underscores the extent to which Trump has smashed one convention after another over the last three weeks.

Vote certification at the local and state level is typically a ministerial task that gets little notice, but that changed with Trump's fierce but fruitless legal challenges and attempts to manipulate the certification process in battleground states he lost.

No evidence has emerged of the widespread voting fraud that Trump and his legal team have repeatedly alleged, only to be slapped down by judges and state election officials.

Trump spoke to reporters in the White House's ornate Diplomatic Reception Room after holding a teleconference with U.S. military leaders stationed across the globe. He thanked them for their service, joked that they shouldn't eat too much turkey, then turned to the election after ending the call. He repeated grievances and angrily denounced officials in Georgia and Pennsylvania, two key states that helped give Biden the win.

Trump's administration has already given the green light for a formal transition to get underway. Yet Trump took issue with Biden moving forward.

"I think it's not right that he's trying to pick a Cabinet," Trump said, even though officials from both teams are already working together to get Biden's team up to speed.

Asked if he'll attend the inauguration, Trump said he knows the answer but doesn't want to say.

He said he'll go to Georgia to rally supporters before two Senate runoff elections that will determine which party controls the Senate. The White House said that rally is expected Dec. 5.

One of the reasons Republicans have stood by Trump and his baseless claims of fraud has been to keep his loyal base energized for those Jan 5 runoffs. But Trump, in his remarks, openly questioned whether that election would be fair, casting suspicions that could dampen Republican turnout.

"I think you're dealing with a very fraudulent system," he said. "I'm very worried about that." He said: "People are very disappointed that we were robbed."

Trump made clear that he will probably never formally concede, even if he said he would leave the White House.

"It's gonna be a very hard thing to concede," he said. "Because we know there was massive fraud."

Electors "will have made a mistake" by affirming Biden's win, he said.

Yet "time isn't on our side."

Will he run again in 2024? Trump said he doesn't "want to talk about 2024 yet."

"This has a long way to go," Trump said, even though he lost.