Mr Trump is likely to choose a more conservative candidate to replace Mr Kennedy, which could shift the highest court in the land to the right for decades to come.

Kennedy, 81, was nominated in 1987 by President Ronald Reagan and served 30 years on the Supreme Court, where he was known as a centrist influence. They include Planned Parenthood v. Casey (1992), which preserved the foundation of legal abortion from Roe v. Wade; the majority decision upholding affirmative action (Fisher v. University of Texas, 2016); and a series of gay-rights rulings, most famously the freedom of same-sex marriage via Obergefell v. Hodges three years ago.

His retirement is a tremendous blow to the Left, especially after Senate Democrats' failure to filibuster the president's first Supreme Court nominee, Neil Gorsuch. Sen. The Republican Party refused to allow the Senate to consider president Barack Obama's nominee for the previous vacancy, moderate Merrick Garland. But so far they have shown zero interest in any sort of delay in getting a second Trump justice onto the bench, with McConnell planning confirmation hearings in August and a Senate debate and vote as soon as possible thereafter.

But a dissenting liberal justice said the court was making a historic mistake by refusing to recognize the ban discriminates against Muslims. Trump said his search for a Supreme Court nominee will "begin immediately" and he intends to make his selection from a list of more than 20 reliably conservative candidates the White House released past year.

With the news that conservative Justice Anthony Kennedy is to retire, a huge opportunity has landed in Donald Trump's lap.

"This will be one of the great constitutional fights of the country's history", Waldman said. The conservative justices on the court give loads of leeway to a president (in this case, a insane one who has been compromised by a foreign power) to dictate immigration policy.

"I expect the nominee to be like Justice Gorsuch, to demonstrate excellence in every respect, and to earn widespread support from the American people, and bipartisan support for confirmation in the Senate", Leo said.

Now, the president gets to nominate Mr Kennedy's replacement.

Kennedy's vote, positioned at the very centre of the court, gives him a place of special prominence among the nine justices.