Barrett, a conservative federal appellate judge, answered questions from senators for the first time on the second day of her Judiciary Committee confirmation hearing. It gave Barrett a chance to respond to Democrats who have opposed her because of her potential as a justice to undermine the 2010 healthcare law and its protection for patients with pre-existing conditions.
Trump has asked the Senate to confirm Barrett before the Nov. 3 election in which he is seeking a second term in office.
Barrett declined to say if she would step aside from any election-related cases that reach the court. The Republican president has said he expects the Supreme Court to decide the election's outcome as he faces Democratic challenger Joe Biden. Barrett said no one at the White House sought a commitment from her on how she would rule on that or any issue.
"It would be a gross violation of judicial independence for me to make any such commitment or for me to be asked about that case," Barrett told the committee of possible election cases.
Barrett declined to say whether she would consider stepping aside, as Democrats have requested, from an Obamacare case due to be argued at the court a week after Election Day in which Trump and Republican-led states are seeking to invalidate the law formally called the Affordable Care Act (ACA).
Barrett noted that the new case centers upon a different legal issue than two previous Supreme Court rulings that upheld Obamacare, which she had criticized. Barrett declined to say how she would approach the new case, but said, "I am not hostile to the ACA."
Barrett also said the White House did not seek her assurance that she would vote to strike down the law.
"Absolutely not. I was never asked - and if I had, that would have been a short conversation," Barrett said.
The Affordable Care Act is Democratic former president Barack Obama's signature domestic policy achievement and has enabled millions of Americans to obtain medical coverage. Democrats have blasted Trump for trying to kill Obamacare amid a deadly pandemic.
Republicans have a 53-47 Senate majority, making Barrett's confirmation a virtual certainty. If confirmed, Barrett, 48, would give conservatives a 6-3 Supreme Court majority. She is Trump's third Supreme Court appointment.
Like other Supreme Court nominees before her, Barrett opted to sidestep some questions on some matters that could come before the court.
Regarding the 1973 ruling called Roe v. Wade that legalized abortion nationwide, Barrett said she would consider the various factors usually applied when justices weigh whether to overturn a precedent.
"I promise to do that for any issue that comes up, abortion or anything else. I'll follow the law," Barrett said.
Senator Dianne Feinstein, the panel's top Democrat, asked Barrett whether she agreed with her mentor, the late conservative Justice Antonin Scalia, that Roe v. Wade can was wrongly decided and should be overturned.
After Barrett declined to answer, Feinstein told her, "So on something that is really a major cause with major effects on over half of the population of this country - who are women, after all - it's distressing not to get a straight answer."
Religious conservatives are hoping the Supreme Court will overturn Roe v. Wade.
Republican committee chairman Lindsey Graham, asked Barrett, a devout Catholic and a favorite of religious conservatives, whether she could set aside her religious beliefs in making decisions as a justice.
"I can," Barrett said.
During her 2017 confirmation hearing after Trump nominated her to her current post on the Chicago-based 7th US Circuit Court of Appeals, Feinstein told Barrett that "the dogma lives loudly in you" - a comment that some Republicans said represented anti-religious bigotry.
Questioned by Feinstein, Barrett declined to say whether she agreed with Scalia that the 2015 Supreme Court ruling called Obergefell v. Hodges legalizing gay marriage nationwide was wrongly decided.
"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.
Asked about George Floyd, a Black man killed by police in Minneapolis in May in an incident that triggered widespread protests, Barrett said the issue was "very, very personal for my family" because of her seven children, two - adopted from Haiti - are Black. Barrett said she and one of her daughters, Vivian, cried together after seeing the video.
"It's a difficult one for us like it is for Americans all over the country," Barrett said.
Barrett said "racism persists" in the United States but declined to give her view on whether it is systemic or how it should be addressed.
Barrett was nominated to a lifetime post on the court on Sept. 26 by Trump to replace the late liberal Justice Ruth Bader Ginsburg. The four-day confirmation hearing is a key step before a full Senate vote by the end of October on Barrett's confirmation.