WASHINGTON, July 8 (Xinhua) -- U.S. President Donald Trump said Sunday that he has yet to decide on his pick for a Supreme Court seat, a day before his self-imposed deadline for an announcement.

"We are close to making a decision," Trump told reporters before returning to Washington from Morristown in the state of New Jersey. "I'll be deciding tonight or tomorrow sometime by 12 o'clock and we're all gonna be meeting at 9 o'clock."

When asked about how many candidates were being considered, Trump said "let's just say it's the four people ... you can't go wrong."

On Twitter, the president said he is looking forward to announcing his final decision on his Supreme Court pick at 9:00 p.m. (0000 GMT on Tuesday) at the White House on Monday.

"An exceptional person will be chosen!" he added.

The U.S. Supreme Court, which has nine members, decides matters that shape the country's politics. It is effectively both the highest appeals panel and a constitutional court.

Trump's Supreme Court pick would replace Justice Anthony Kennedy, who announced his retirement late last month.

Kennedy, 81, is the court's current longest-serving member and second-oldest justice and is widely thought to be a moderate and pivotal swing vote in the highest federal court.

Liberal advocacy groups and others are concerned that Trump's pick to fill Kennedy's seat could move the court more solidly to the right and revisit landmark rulings on abortion access, gay marriage and other hot-button issues.

The Trump administration has been reportedly preparing information materials on four potential nominees: appeals court judges Brett Kavanaugh, Raymond Kethledge, Amy Coney Barrett and Thomas Hardiman.

It would be the second time in two years that Trump has made a Supreme Court pick.