Still, Trump has recounted how close he came to selecting Hardiman, who was recommended by the President's sister and sometime confidante, retired federal judge Maryanne Trump Barry. She served with the Pennsylvania-based Hardiman on the US Court of Appeals for the 3rd Circuit.
And Hardiman's working-class roots - his time driving a taxi during his days as a law student at Georgetown University - have been cited as an attribute inside the White House, along with his conservative rulings. His boosters, sensing this weekend that Hardiman could be ascending on the President's list, have been busy making phone calls to friends in Trump's inner circle.
"He's got a story that's compelling beyond the taxicab," former senator Rick Santorum, (R), a friend of Hardiman's, said.
"I'm talking to people about his service work with his church in West Virginia and about how he has helped people seeking asylum from communist countries. He speaks Spanish. His wife comes from a Democratic family, and he knows how to engage with all kind of people, not just Republicans."
Santorum added that picking Hardiman could help Trump bolster his support in Pennsylvania, a crucial state in his Electoral College victory in 2016 and a 2020 battleground.
Previously, the three front-runners for the nomination have been seen as Kavanaugh, who serves on the US Court of Appeals for the District of Columbia Circuit; Michigan's Kethledge, from the 6th Circuit; and Indiana's Barrett, from the 7th Circuit.
All three candidates remain in contention, but Trump has revived talk of Hardiman because he has not felt compelled, yet, to tap one of them.
Senate Majority Leader Mitch McConnell, (R), who will lead the confirmation fight on Capitol Hill, spoke to Trump by phone on Saturday.
The officials underscored that McConnell did not push any choice on the President. But, the officials said, McConnell did note that Hardiman and Kethledge could fare well in the Senate because their reputations and records were not as politically charged as others on the President's shortlist of nominees.
Trump is scheduled to announce his decision at 1pm NZT, and it is unclear how much of the last-minute maneuvering is geared to keeping the President's choice a secret. But supporters and detractors of the candidates are pushing hard.
Trump is searching for a replacement for Justice Anthony Kennedy.
Kennedy's retirement has given conservatives their first hope in decades for a court that would strike down Roe vs Wade, the landmark decision that legalised abortion. But, at the moment, it is liberals who are focused on making this a galvanising issue.
In interviews on talk shows, supporters of a conservative court pick often stopped short of saying that the President's nominee would sink Roe.
Leonard Leo, a Federalist Society leader who has helped vet the nominees on the President's public shortlist, used an interview on Fox News Sunday to accuse opponents of any nominee of diversion.
"We only have a single individual on the court who has expressly said he would overturn Roe," Leo said, referring to Justice Clarence Thomas, the only one on the current Bench to have voted against the 1992 Planned Parenthood vs Casey decision reaffirming Roe. "So I think it's a bit of a scare tactic and rank speculation more than anything else."
In an interview on NBC News's Meet the Press, when asked about Roe, Senator Roy Blunt, (R), said that "these judges, whichever one's nominated, should follow the Ginsburg strategy, which has been: no hints, no foretelling of how they're going to determine" controversial cases.
That was a reference to Justice Ruth Bader Ginsburg, who said during her 1993 hearing that it would be "wrong for me to say or preview in this legislative chamber how I would cast my vote." Conservatives have seized on that answer and called it "the Ginsburg rule" - but at another point in the hearing, Ginsburg said women had a "right to decide whether or not to bear a child."
During the 2016 campaign, and in subsequent interviews, Trump repeatedly assured conservative voters that his nominees would scrap the 45-year-old decision that legalised abortion across the US.
In 2016, he told Fox News' Chris Wallace that Roe would be overturned if he got to appoint "two or three" justices, "because I am putting pro-life justices on the court." Kennedy had effectively preserved Roe by joining the controlling opinion in Planned Parenthood vs Casey; every judge on the Trump shortlist is seen as a likely vote against abortion rights.
"He is certainly the first major-party nominee who went on to be president to put a litmus test on Supreme Court justices, and that was to actually overturn Roe vs Wade," Ilyse Hogue, president of NARAL Pro-Choice America, said on Fox News.
"We believe him. He's got a vice-president who committed to, you know, throw Roe on an ash heap of history. So we think that's the mind-set that many Americans are actually going into this with because it was such a vocal talking point for him."
After an initial burst of enthusiasm about the court opening, Republican politicians have characterised any questions about Roe's fate as scaremongering by Democrats.
At a weekend rally in Wisconsin where she was joined by House Speaker Paul Ryan, (R), Republican US Senate hopeful Leah Vukmir said local Senator Tammy Baldwin, (D), "has let our unborn down," specifically by skipping a vote on legislation that would ban abortion after 20 weeks of pregnancy. In a short scrum with reporters after the rally, however, Vukmir refused to say whether she wanted the Supreme Court to undo Roe or Casey.
"The left is trying to politicise this by bringing up this case, that case; will you undo this, undo that. My focus is on somebody who will stand for the Constitution," Vukmir said. "I'm not going to comment on those particular cases right now."
Wisconsin is one of 10 states carried in 2016 by Trump where a Democratic senator is facing re-election this year. It's also one of 20 states where an end to Roe would start a chain of events likely to restrict abortion rights; some states have "trigger laws" that would make abortion immediately illegal, while some have passed abortion limitations that are blocked by Roe.
While public polling on abortion finds support for a number of potential abortion restrictions, the popularity of Roe itself remains high. As they've put together a campaign against the President's nominee, Democratic groups have found that informing voters of a looming threat to Roe - one that few saw as likely before the 2016 election - is one of their strongest messages.
"The vast majority of American people, shown by poll after poll, want Roe vs Wade to be preserved," Senator Richard Blumenthal, (D), said on ABC News' This Week. "They want protections for millions of Americans against pre-existing conditions to be sustained. They want these voting rights and gay rights and other rights to be not only preserved, but also enhanced."
On CBS News' Face the Nation, Senator Christopher Coons, (D), echoed Blumenthal, saying the next Supreme Court nominee could get the chance to undermine the Affordable Care Act and "reproductive freedom."
Democrats, bearish on their chances of stopping any nominee, believe they can put pressure on Republican senators Susan Collins and Lisa Murkowski if the nominee is on record wanting to end Roe.
If neither senator breaks, Democrats still believe that they can drive down public support for the nominee by focusing on threats to Roe, gay rights, the ACA and environmental regulations - even in Indiana, North Dakota and West Virginia, ruby-red states whose Democratic senators backed Trump's first Supreme Court nominee, Neil Gorsuch.
