At a White House swearing-in ceremony, Trump stood next to Justice Brett Kavanaugh and said he'd been "proven innocent" of the sexual assault allegations that threatened to derail him in a Senate confirmation process revealing the depth of the left-right split tearing through U.S. politics.
Trump also tweeted that previous evening had been a "great" night at the White House honoring Justice Kavanaugh.
As Trump, the other eight court justices and a number of Republican senators crucial to the confirmation process watched, retired Justice Anthony Kennedy administered the judicial oath to Kavanaugh. He said the high court "is not a partisan or political institution" and assured he took the job with "no bitterness".
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Conservative radio talk show host Rush Limbaugh said Washington, D.C. maybe become "uninhabitable for a while" if the Democrats do not retake the House in November's midterm elections.
Democrats fought tooth and nail to stop Kavanaugh's candidacy, claiming that the accomplished, conservative-minded judge was not suited to the Supreme Court, which will now tilt decisively to a more Republican-friendly panel.
A spokesperson at the National Republican Congressional Committee, which works on House races, said it saw a 418 percent increase in online donations in the first week of October - when Kavanaugh was undergoing an FBI investigation - compared to the first week of September.
He'll also sit on the committee that oversees the court's cafeteria, which is open to the public. On the Supreme Court, I will seek to be a force for stability and unity. He has denied the allegations.
Mr Kavanaugh's elevation to the high court had been considered safe until California university professor Christine Blasey Ford went public with explosive allegations that he had sexually assaulted her in 1982, while they were in high school.
"The Senate confirmation process was contentious and emotional", Kavanaugh said.
McConnell disagreed with President Donald Trump's prediction that she will "never recover" from her vote, demonstrating once again that as the leader of a supposed conservative Republican party, he is out of step with rank-and-file conservatives.
During the Supreme Court nomination of Judge Merrick Garland by Obama in 2016, Republicans argued that the next president should be the one to choose who the next nominee would be for the Supreme Court seat left vacant by the death of Justice Antonin Scalia.
Trump lauded Kavanaugh as a "brilliant jurist" and blamed Democrats for the focus on decades-old allegations of sexual misconduct that dominated debate in the weeks before the nominee's Senate confirmation on Saturday. But the Democrats' outrageous antics in the Kavanaugh fight have awakened a sleeping Republican giant.
Kavanaugh sought to play down the political maelstrom that surrounded his confirmation, and said he would serve "one nation". Murkowski voted against advancing Kavanaugh's nomination and "present" on the final vote.
Justice Kavanaugh can be expected to cast crucial votes on those issues as well as gun control, immigration, voting rights and others.