WASHINGTON — President Donald Trump says he doesn't "remember much" about a March 2016 meeting with his campaign foreign policy adviser that is now front-and-center in special counsel Robert Mueller's Russia probe.

Speaking to reporters outside the White House, Trump says: "It was a very unimportant meeting. It took place a long time ago. I don't remember much about it."

Trump's former campaign adviser, George Papadopoulos, has pleaded guilty to lying to the FBI about his contacts with Russian officials. Papadopoulos later told agents he used that gathering to offer to arrange a meeting between Trump and Russian President Vladimir Putin.

The White House argues Papadopoulos was merely a campaign "volunteer" whose claims shouldn't be taken seriously.