U.S. President Donald Trump's Supreme Court nominee, Amy Coney Barrett, on Tuesday told her Senate confirmation hearing that her religious views would not affect her decisions on the bench and declined to say whether she believes the landmark 1973 ruling legalizing abortion nationwide was properly decided.

The Senate's judiciary committee hearing presents Barrett with a chance to respond to Democratic lawmakers who have been unified in opposing her primarily on what they say would be her role in undermining the Obamacare health-care law and its protection for patients with pre-existing conditions.

Barrett, facing questioning by senators for the first time, declined to say if she would consider stepping aside from the case, as Democrats have requested, saying she would follow rules on recusal, which give individual justices the final say.

"That's not a question I can answer in the abstract," Barrett said.

In responding to questions about abortion, which was legalized by the Supreme Court in a 1973 ruling called Roe v. Wade, Barrett said she would, as in other cases, consider the various factors usually applied when justices weigh whether to overturn a precedent.

Sen. Dianne Feinstein, the panel's top Democrat, asked Barrett whether she believed Roe v. Wade, which recognized a woman's constitutional right to terminate a pregnancy, was properly decided. She declined to answer.

Feinstein told Barrett it was "disturbing" that she would not give an answer.

Religious conservatives are hoping the Supreme Court will overturn Roe v. Wade.

'I'll follow the law'

Barrett pledged to follow the rules that bind justices when considering whether to overturn precedent.

"I promise to do that for any issue that comes up, abortion or anything else. I'll follow the law," Barrett said.

Judiciary committee chair Lindsey Graham speaks during Tuesday's confirmation hearing. Graham and his fellow Republicans are looking to install Barrett on the Supreme Court ahead of the Nov. 3 election. (Stefani Reynolds/The Associated Press)

Republican Sen. Lindsey Graham, the committee's chairman, opened the questioning by asking her about her conservative legal philosophy known as originalism, in which laws and the constitution are interpreted based on the meaning they had at the time they were enacted.

"That meaning doesn't change over time and it's not for me to update it or infuse my own policy views into it," Barrett said.

Graham asked Barrett, a devout Catholic and a favourite of religious conservatives, whether she could set aside her religious beliefs in making decisions as a justice.

"I can," Barrett said.

Barrett called the late conservative Justice Antonin Scalia, for whom she served as a clerk two decades ago, as her mentor, but said she would not always rule the same way as him.

"You would not be getting Justice Scalia, you would be getting Justice Barrett. That is so because originalists don't always agree," she said.

Questioned by Feinstein, Barrett would not comment on whether she agreed with Scalia that the 2015 Supreme Court ruling legalizing gay marriage nationwide was wrongly decided.

Demonstrators for and against Barrett's nomination gather in D.C.:

"I have no agenda and I do want to be clear that I have never discriminated on the basis of sexual preference and I would not discriminate on the basis of sexual preference," Barrett said.

Barrett declined to answer when Feinstein asked her whether the U.S. Constitution gives the president the authority to unilaterally delay a general election under any circumstances. Barrett said if such a question came before her as a judge she would have to hear arguments and read legal briefs before deciding.

"If I give off-the-cuff answers then I would be basically a legal pundit. And I don't think we want judges to be legal pundits. We want judges to approach cases thoughtfully and with an open mind," Barrett said.

Barrett was nominated to the court by Republican President Donald Trump late last month following the death of liberal Justice Ruth Bader Ginsburg.

Democrats unlikely to block confirmation

She could be on the Supreme Court in time for the Nov. 10 arguments in a case in which Trump and Republican-led states are seeking to invalidate the 2010 Affordable Care Act, Democratic former president Barack Obama's signature domestic policy achievement that has enabled millions of Americans to obtain medical coverage.

It's also possible she would be asked to weigh in on election disputes.

Republicans have a 53-47 Senate majority, leaving Democrats with little to no chance of blocking Barrett's confirmation.

Barrett, 48, would tilt the Supreme Court further to the right and give conservative justices a 6-3 majority, making even the unexpected victories on which liberals have prevailed in recent years, including abortion and gay rights, rarer still.

WATCH l Barrett vows to follow the law, not make it:

U.S. political divisions centre stage at Amy Coney Barrett confirmation hearing

14 hours ago

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The deep-seated divisions between Republicans and Democrats were front and centre during the first day of Senate confirmation hearings for Supreme Court nominee Amy Coney Barrett. Coney Barrett says she wouldn’t let her personal beliefs impact her judgements. 2:01

Trump's nomination of Barrett came late in an election cycle when Republican control of both the White House and Senate is at stake. The confirmation hearing format has changed because of the COVID-19 pandemic, with the public excluded and some senators participating remotely.

The hearing is a key step before a full Senate vote by the end of October on Barrett's confirmation to a lifetime job on the court.