The president is expected to announce his official nominee in a prime-time announcement Monday night.
Trump indeed said during the 2016 campaign that he would put "pro-life justices on the court", thrilling his grassroots base although polls show most Americans support abortion rights.
Trump tweeted on Sunday that: "An exceptional person will be chosen!"
CBS has learned he's narrowed the list of contenders to four appeals court judges.
Unlike presidents or members of Congress, however, Supreme Court justices in the United States do not have terms - they usually serve until they resign or die, giving presidents who select them a judicial legacy sometimes lasting decades beyond their terms in office. He is an evangelical Christian whose book, Lead Yourself First, uses President Dwight Eisenhower, primatologist Jane Goodall, Winston Churchill, Martin Luther King Jr. and others as examples of "leaders who have used solitude to function more effectively".More news: Battle lines drawn over abortion ahead of Trump's supreme court pick
Neil Gorsuch, 50, who was appointed by Mr Trump previous year, is already one of the most conservative of the court's nine justices.
Kavanaugh said, "My judicial philosophy is straightforward". The favorite of White House Counsel Donald McGahn, Kavanaugh is also considered a safer pick than some of the more partisan choices who were on the president's shortlist. "Whoever is nominated, whoever he or she is, if they're confirmed, they're going to be there for a long time".
Hardiman, who turned 53 on Sunday, lost out to Gorsuch in 2017. Barry served alongside Hardiman as a federal appeals judge on the 3rd Circuit before stepping down past year. Given Trump's known habit of leaning on family ties and valuing loyalty above all, that could be decisive.
Judge Kavanaugh now faces what could be a hard fight for confirmation by the US Senate, where Republicans hold only a slim majority.
Republican Senator Susan Collins of ME has said she couldn't support a nominee that doesn't respect legal precedent and would overturn the "settled law" of Roe V. Wade. "And I expect we will do that on sort of a normal timetable, a couple of months". Although the statement is undoubtedly accurate, it is likely to be seized on by supporters of abortion rights as they try to convince moderate Republican senators that Barrett might vote to overturn the 1973 Roe v. Wade decision declaring a woman's constitutional right to abortion. The chief justice John Roberts and justices Clarence Thomas, and Ruth Bader Ginsburg served on the same court.
In a primetime announcement at the White House, Mr Trump praised his pick as a "brilliant jurist".More news: Emotional Hamilton rises to the occasion with record British GP pole
President Donald Trump crosses the South Lawn upon arrival at the White House on July 8, 2018 in Washington, DC.
McConnell has promised a vote on the nomination before the November midterms, ensuring the outcome will be an issue before voters.
The announcement was set to spark an intense fight between Republicans and Democrats during the ensuing confirmation process in the US Senate.
Trump a year ago appointed Neil Gorsuch, who has already become one of the most conservative justices, after Senate Republicans in 2016 refused to consider Democratic former President Barack Obama's nominee Merrick Garland to fill a vacancy left by the death of conservative Justice Antonin Scalia.
"It's insane" over there, said a source close to the process.
"They just didn't get it, but they do now!"More news: Trump administration seeks more time to reunite families