President Trump has completed the interview process for Supreme Court candidates after speaking with six judges, a source with knowledge of the selection process told Fox News – with three finalists in particular leading the field.

The president and his vetting team have moved quickly ahead of an expected announcement on Monday.

While liberal advocacy groups and others are gearing up for a major confirmation fight, Trump is charging ahead with an imminent decision to fill the seat of retiring Justice Anthony Kennedy, and potentially move the court more solidly to the right.

Fox News is told that Trump has interviewed six candidates: Appeals court judges Brett Kavanaugh, Raymond Kethledge, Amy Coney Barrett, Amul Thapar, Joan Larsen and Thomas Hardiman. The interviews comprised seven conversations – Trump talked to one candidate twice.

Multiple sources indicated Kavanaugh, Kethledge and Barrett are currently the focus of attention.

Vice President Pence also has met with "leading candidates," Republican sources told Fox News, adding that Pence met with Kavanaugh at the U.S. Naval Observatory on Wednesday.

The president also had an additional phone call with Utah GOP Sen. Mike Lee, though Fox News is told the call was not a formal interview and more to ask Lee his thoughts on who would make a good nominee.

Multiple sources told Fox News that while Lee is on the president’s broader list of 25 potential candidates he has vowed to choose from, he is not currently under consideration to replace Kennedy.

An intense pressure campaign is being waged on the sidelines, by conservative and liberal interests alike.

MEDIA TOUTING -- AND TARGETING -- AMY BARRETT

Democrat-aligned groups are pressuring potential swing senators – especially moderate Republicans like Alaska’s Lisa Murkowski and Maine’s Susan Collins – to oppose Trump’s eventual nominee, arguing in part that landmark decisions like abortion-legalizing Roe v. Wade could be at risk.

Conservative groups, meanwhile, have sought to sway the president’s decision-making – including a whisper campaign against Kavanaugh over everything from his ties to the George W. Bush administration to a past ObamaCare ruling. While some critics have claimed that 2011 case helped pave the way for the law’s individual mandate to be upheld by the Supreme Court, others say the criticism is unfounded – and Kavanaugh actually spoke out against the mandate.

Kavanaugh remains very much in the running, however, while Kethledge’s stock is said to be rising.

Some conservatives have pointed to Kethledge as a potential justice in the mold of Neil Gorsuch, Trump's first Supreme Court nominee last year. Both Kethledge and Gorsuch once served Kennedy as law clerks, as did Kavanaugh. Kethledge, a Michigan Law graduate, would add academic diversity to a court steeped in the Ivy League.

As Trump prepares to name the second high court pick of his presidency, speculation also has focused on Barrett, a former law clerk to Justice Antonin Scalia and a longtime Notre Dame Law School professor who serves on the 7th U.S. Circuit Court of Appeals. Conservative groups rallied around Barrett after her confirmation hearing last year featured questioning from Democrats over how her Roman Catholic faith would affect her decisions.

The Associated Press contributed to this report.