WASHINGTON — President Donald Trump's team is hoping to nominate a successor to Supreme Court Justice Anthony Kennedy soon, according to White House insiders working on the process.

"We have to pick a great one. We have to pick one that's going to be there for 40 years, 45 years," Trump said at a campaign rally in Fargo, North Dakota, on Wednesday night, suggesting that his nominee will be young enough to serve that long on the court, where the average retirement age in recent years has been 83.

Among front-runners, according to those involved in the process, is Brett Kavanaugh of Maryland. He serves on the U.S. Court of Appeals for the District of Columbia and is a former Kennedy law clerk, as was Neil Gorsuch, Trump's first Supreme Court nominee, who succeeded Antonin Scalia.

Leonard Leo, who has taken a leave of absence from the conservative Federalist Society to help in the selection process, said the nominee will be a judge.

"It will certainly be someone with a demonstrated judicial record," Leo said.

That suggests that nonjudges on list of potential candidates released by the White House last November, such as Sen. Mike Lee, R-Utah, are not current front-runners for a Supreme Court nomination.

Others mentioned by insiders are all federal appeals court judges, including Thomas Hardiman of Pennsylvania, who serves alongside Trump's sister on the 3rd Circuit. Hardiman and Gorsuch were the finalists last year when the president was choosing Scalia's successor.

The rest of the short list includes two judges from the 6th Circuit Court of Appeals — Raymond Kethledge of Michigan and Amul Thapar, who is from Kentucky, home state of Senator Majority Leader Mitch McConnell — and Amy Coney Barrett of Indiana on the 7th Circuit Court of Appeals.