Kavanaugh was nominated to the federal appeals court by former President George W. Bush, who said he selected Kavanaugh "because of the force of his mind, the breadth of his experience and the strength of his character".
"We have four great candidates".
With reality television-style suspense, he had kept everyone guessing up until the last moment.
Trump's pick, if confirmed by the Senate, will replace Justice Anthony Kennedy, who has always been the swing vote on the divided court.
But, they 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.
"I am grateful to you and I am humbled by your confidence in me".
Kethledge, who was a clerk for Kennedy in 1997-98, has been described as very similar ideologically to Gorsuch.
Judge Kavanaugh recently voiced disagreement with a court decision allowing an undocumented teenage immigrant to have an abortion. He also has taken an expansive view of executive power and has favoured limits on investigating the president. The court could also be called upon to render judgment on issues of personal significance to Trump and his administration including matters arising from Special Counsel Robert Mueller's ongoing Russia-related investigation and several civil lawsuits pending against Trump. He has been a judge on the federal appeals court in Washington since 2006.
Each of the nine justices serves a lifetime appointment.
Kavanaugh potentially could serve on the high court for decades.
The battle for Senate confirmation of Trump's Supreme Court pick is likely to be one of the most intense. But Judge Kavanaugh may not be so accommodating.
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.
The front-runner was a front-runner for a reason.
Trump announced his pick on prime-time television, calling Kavanaugh "a judge's judge" with a "proven commitment to equal justice under the law".
He is the kind of judge a President Jeb Bush or Mitt Romney would have picked - a man with an established legal pedigree and a reputation as a reliably conservative jurist. When the court he serves on upheld a New Jersey law requiring a gun owner to obtain a permit to carry a gun in public places and to show that he has "a justifiable need" to carry the gun, Hardiman dissented, chastising the majority for upholding a law that dates to 1966 (and arguably 1924) as insufficiently long-standing.
Any of the candidates on Trump's short list would probably move the court to the right. Without Republican defections, however, Senate rules leave Democrats with scant options to block confirmation of Trump's nominee.
Mr Trump is securing a conservative judiciary for a generation.
Judge Kavanaugh now faces what could be a hard fight for confirmation by the US Senate, where Republicans hold only a slim majority.
A nominee needs a simple majority of 51 votes to be confirmed. Kyl, a former member of Republican leadership, was Senator for Arizona for 18 years from 1995 to 2013. Feinstein is the ranking Democrat on the Judiciary Committee.
Judge Kavanaugh said he would begin meetings with senators on Tuesday.
The White House and Republican party want the nomination in the bag before November's mid-term elections.
One red-state Democratic senator up for re-election this year - Sen. Joe Donnelly of Indiana, Heidi Heitkamp of North Dakota, Doug Jones of Alabama, Joe Manchin of West Virginia and Diane Feinstein of California. Hardiman was said to be the runner-up to succeed Antonin Scalia, the seat Neil Gorsuch eventually occupied after being confirmed in 2017.
Collins has said she would not back a nominee who seeks to overturn Roe v. Wade, the 1973 court case that legalized abortion.