Lawmakers fired the opening shots Tuesday in a bitter political battle to confirm Brett Kavanaugh, the conservative judge tapped by President Donald Trump to fill a key vacancy on the US Supreme Court.

If confirmed by the Senate, Kavanaugh would help cement a rightward tilt on America's top court, potentially shaping many aspects of US society for decades to come, including women's access to abortions.

Trump on Monday nominated Kavanaugh, 53, as his pick to succeed retiring Justice Anthony Kennedy, saying the federal judge has "impeccable credentials, unsurpassed qualifications, and a proven commitment to equal justice under the law."

Kavanaugh's job-for-life appointment would lock down a conservative majority on the court following the departure of Kennedy, who acted as swing vote on a number of key issues including the legalization of gay marriage across America.

Opposition figures wasted no time in assailing Kavanaugh, warning his confirmation would usher in the erosion of civil liberties and long-held rights, while conservatives were quick to drum up support for the nominee.

In selecting Kavanaugh, Trump "has put women's reproductive rights and vital health care protections... at grave, grave risk," Senate Minority Leader Chuck Schumer told reporters outside the Supreme Court on Tuesday.

"Now is the time for the American people to make their voices heard, loudly, clearly, from one end of this country to the other."

Liberal Senator Bernie Sanders said Kavanaugh would serve as a "rubber-stamp for an extreme, right-wing agenda pushed by corporations and billionaires."

But the Senate's top Republican, Majority Leader Mitch McConnell, hailed a "superb choice" in Kavanaugh and urged senators to "put partisanship aside and consider his legal qualifications with the fairness, respect and seriousness that a Supreme Court nomination ought to command."

The conservative action group Judicial Crisis Network immediately launched a website called featuring an advertisement for the nominee who "applies the Constitution just as it was written."

- Little wiggle room -

GETTY IMAGES NORTH AMERICA/AFP / CHIP SOMODEVILLAJudge Brett Kavanaugh poses for photographs before meeting with Senate Majority Leader Mitch McConnell

Calls to put party politics aside are likely to fall on deaf ears in Washington.

The appointment of Supreme Court justices was once a fairly civil and bipartisan affair: when Ruth Bader Ginsburg was nominated in 1993, Senators voted 96-3 to confirm her.

Not any more.

Kavanaugh's nomination sets the stage for a brutal confirmation battle, a blueprint for which was established by Republicans in 2016 when they denied a hearing to Merrick Garland, Barack Obama's choice to fill the seat left vacant following the death of conservative justice Antonin Scalia.

When Trump finally tapped Neil Gorsuch to fill the vacancy, McConnell resorted to changing procedural rules so he could be approved by a simple majority instead of the traditional 60-40 threshold.

But Republicans hold the narrowest of majorities in the Senate: 51 Republicans, against 49 Democrats and Independents. With ailing Republican John McCain unable to vote, they have little wiggle room.

During the Gorsuch vote, three Democrats from conservative states ended up siding with Republicans -- a question now is whether they will support Kavanaugh.

One of these Democrats, Senator Joe Manchin from West Virginia, said his vote depends on how Kavanaugh performs during confirmation hearing, particularly on the issue of whether patients with "pre-existing conditions" can retain access to health care.

Observers were also looking to two moderate Republicans, Susan Collins of Maine and Lisa Murkowski of Alaska, both of whom support abortion rights.

"I will conduct careful, thorough vetting of the president's nominee to the Supreme Court," Collins said in a statement.

Kavanaugh must now meet with senators ahead of any confirmation hearings to explain his positions.

"If confirmed by the Senate, I will keep an open mind in every case, and I will always strive to preserve the Constitution of the United States and the American Rule of Law," he said.

- Bush era -

Kavanaugh worked for president George W. Bush, who appointed him in 2003 to the US Court of Appeals in Washington -- where he was finally confirmed in 2006 after years of Democratic obstruction.

He is also a robust supporter of the executive power of the presidency.

AFP / Gal ROMAUS Supreme Court

Kavanaugh, who grew up in Washington as the son of a schoolteacher, has the reputation of a staunch conservative, one who many Republicans no doubt hope could help overturn Roe v Wade, the landmark 1973 decision that guarantees women the right to an abortion.

He has ruled on hundreds of cases, and contributed to prosecutor Kenneth Starr's report into president Bill Clinton's affair with White House intern Monica Lewinsky, which outlined grounds for Clinton's impeachment.

Later he was part of Bush's legal team working on the 2000 Florida recount, which resulted in Bush winning the presidency.

While Democrats tried to paint Kavanaugh as an extremist, Republicans said he was the type of moderate Bush might have appointed.

Republican Senator Thom Tillis called him "a mainstream and fair-minded jurist," and number two Republican Senator John Cornyn said he would be "fair and impartial."