President Donald Trump has picked Brett Kavanaugh, a politically connected conservative judge, for the Supreme Court, setting up a ferocious confirmation battle with Democrats as he seeks to shift the nation’s highest court further to the right.

A favourite of the Republican legal establishment in Washington, Mr Kavanaugh, 53, is a former law clerk for retiring Justice Anthony Kennedy.

Like Mr Trump’s first nominee last year, Justice Neil Gorsuch, Mr Kavanaugh would be a young addition who could help remake the court for decades to come with rulings that could restrict abortion, expand gun rights and roll back key parts of Obamacare.

“There is no one in America more qualified for this position and no one more deserving,” said Mr Trump, who called Mr Kavanaugh “one of the sharpest legal minds of our time”.

With Mr Kavanaugh, Mr Trump is replacing a swing vote on the nine-member court with a staunch conservative.

Mr Kavanaugh, who serves on the Court of Appeals for the DC Circuit, is expected to be less receptive to abortion and gay rights than Kennedy was. He also has taken an expansive view of executive power and has favoured limits on investigating the president.

A senior White House official said Mr Trump made his final decision on the nomination on Sunday evening, then phoned Mr Kavanaugh to inform him.

The official said Mr Trump decided on Mr Kavanaugh, a front-runner throughout the search process, because of his large body of jurisprudence cited by other courts, describing him as a judge that other judges read.

On Monday, Mr Trump phoned retiring Justice Kennedy to inform him that his former law clerk would be nominated to fill his seat. Mr Trump signed Mr Kavanaugh’s nomination papers on Monday evening in the White House residence.

Top contenders had included federal appeals judges Raymond Kethledge, Amy Coney Barrett and Thomas Hardiman.

Relishing the guessing game beyond the White House gates, Mr Trump had little to say about his choice before the announcement.

Some conservatives have expressed concerns about Mr Kavanaugh, questioning his commitment to social issues such as abortion and noting his time serving under President George W Bush as evidence he is a more establishment choice.

But his supporters have cited his experience and wide range of legal opinions.

Ahead of his announcement, Mr Trump tweeted about the stakes: “I have long heard that the most important decision a U.S. President can make is the selection of a Supreme Court Justice – Will be announced tonight at 9:00 P.M.”

With Democrats determined to vigorously oppose Mr Trump’s choice, the Senate confirmation battle is expected to dominate the months leading up to November’s midterm elections.

Senate Republicans hold only a 51-49 majority, leaving them hardly any margin if Democrats hold the line. Democratic senators running for re-election in states Mr Trump carried in 2016 will face pressure to back his nominee.

Republican Senator John Kennedy of Louisiana said he was bracing for a tough confirmation battle as Democrats focus on abortion.

Mr Kennedy, a member of the Judiciary Committee, which will get the first chance to question the nominee, predicted a “rough, tough, down in the dirt, ear-pulling, nose-biting fight.”

Mr Trump’s success in confirming conservative judges, as well as a Supreme Court justice, has cheered Republicans amid concerns about his limited policy achievements and chaotic management style.

Of the court’s liberal justices, Ruth Bader Ginsburg is 85 and Stephen Breyer turns 80 next month, so Mr Trump may well get another opportunity to cement conservative dominance of the court for years to come.

Trump Supreme Court
Brett Kavanaugh, the president’s Supreme Court nominee, speaks the East Room of the White House (Evan Vucci/AP)

Mr Kavanaugh is likely to be more conservative than Justice Kennedy on a range of social issues. At the top of that list is abortion.

A more conservative majority could be more willing to uphold state restrictions on abortion, if not overturn the 45-year-old landmark Roe v Wade decision that established a woman’s constitutional right.

Mr Kennedy’s replacement also could be more willing to allow states to carry out executions and could support undoing earlier court holdings in the areas of racial discrimination in housing and the workplace.

Mr Kennedy provided a decisive vote in 2015 on an important fair housing case.

While the president has been pondering his choice, his aides have been preparing for what is expected to be a tough confirmation fight.

The White House said on Monday that former Arizona Senator Jon Kyl would guide Mr Trump’s nominee through the gruelling Senate process.

Mr Kyl, a former member of Republican leadership, served on the Senate Judiciary Committee before retiring in 2013.

The White House hopes Mr Kyl’s close ties to Senate Republicans will help smooth the path for confirmation.