Republican Sen. Chuck Grassley of Iowa, in his opening statement, quoted from Justice Ginsburg’s eulogy for Justice Scalia in a likely short-lived attempt to appeal to bipartisanship ahead of what will be a contentious week.

“The Senate is now tasked with carrying out perhaps its most solemn duty under the Constitution, as we go through this process, we should heed Justice Ginsburg's words with a shared reverence for the Court, and its part of our constitutional system,” he said.

Gearing up for Democratic attacks, Grassley then said he expects his colleagues will do “anything to derail the confirmation of a Republican nominee" and cautioned them not to allow this hearing to unfold as Justice Brett Kavanaugh’s did.

Expecting her Catholic faith to come up in the hearing, Grassley also reminded everyone of Barrett's rights.

“Let me remind everyone that Article One clearly prohibits religious tests for serving in public office,” Grassley continued. “I expect that you will follow the example of Justice Ginsburg, a nominee should offer no forecast, no hints of how he or she will vote, because that's the role of a judge,” he said, in an apparent reference to the so-called “Ginsburg Rule” con concerning what nominees can say at confirmation hearings.

Setting the tone for Democrats, Ranking Member Sen. Dianne Feinstein, D-Calif., gave a nod to the legacy of the late Justice Ginsburg -- calling her a "standard-bearer for justice” -- before offering a preview of what her Democrats will focus on: Judge Barrett’s views on the Affordable Care Act and what she called the “consequences” of a rushed nomination.

“In filling Judge Ginsburg's seat, the stakes are extraordinarily high for the American people both in the short term and for decades to come. Most importantly, health care coverage, for millions of Americans, is at stake with this nomination,” Feinstein said. “So, over the course of these hearings, my colleagues and I will focus on that subject.”

“We will examine the consequences if, and that's a big " if," Republicans succeed in rushing this nomination through the Senate, before the next president takes office,” she continued, despite Republicans saying they're confident they can get a final vote before Election Day.

The Court is slated to hear oral arguments on the Affordable Care Act, which the Trump administration is seeking to overturn, one week after the election on Nov. 10., raising concern among Democrats on its fate amid a pandemic.

“We can't afford to go back to those days, when Americans could be denied coverage or charged exorbitant amounts. That's what's at stake for many of us, for America, with this nomination,” she said.

Feinstein also quoted Graham from when he previously said that a Supreme Court nominee shouldn't be confirmed when voting is underway.

Graham began his opening statement by reminding his colleagues of the bipartisan Senate support for both the Justice Ruth Bader Ginsburg and Justice Antonin Scalia nominations.

“I don't know what happened between then and now. I guess we can all take some blame,” Graham said. “But I just want to remind everybody, there was a time, in this country, where someone like Ruth Bader Ginsburg was seen by almost everybody as qualified for the position of being on the Supreme Court.”

After he ticked through a list of Judge Barrett’s qualifications, he addressed the matter of the confirmation vote arising in an election year -- a point of contention with Democrats as Republicans prevented a hearing and vote on former President Barack Obama's nomination of Judge Merrick Garland in 2016.

“We're confirming the judge in an election year after the voting has occurred. What will happen is that my Democratic colleagues will say this has never been done and they're right in this regard, I don't think anybody has been confirmed in an election year past July,” Graham said, before getting to what he called his "bottom line."

“The bottom line here is that the Senate is doing its duty constitutionally,” he said. “As to Judge Garland, the opening that occurred with the passing of Justice Scalia, was in the early part of an election year. The primary process had just started.”

Graham also said the hearing will likely not change Barrett's path to the court, noting that Republicans have the votes.

“This is probably not about persuading each other, unless something really dramatic happens. All Republicans will vote yes, and all Democrats will vote no. And that will be the way the breakout of the vote, but the hearing is a chance for Democrats to dig deep into her philosophy, appropriately ask her about the law, somehow she would be different, what's on her mind,” he said.

The four-day confirmation hearing for Judge Barrett is underway in the Senate Judiciary Committee.

Republicans are expected to push for a vote before Election Day as Democrats will try to stop her from turning the court sharply conservative for decades to come.

Committee chairman Sen. Lindsey Graham, R-S.C., is giving his opening statement first, to be followed by Ranking Member Sen. Diane Feinstein, D-Calif. Both appeared in-person and wore masks into the room.

Senators will follow with 10-minute opening statements before Judge Barrett is then introduced, sworn in and gives her opening statement.

Members were given the option of appearing and questioning the witness in person or remotely due to the coronavirus pandemic. Each senator makes their own determination.

The Capitol Hill press pool reported Barrett’s children, in attendance with her Monday, were running down the Capitol Hill hallways and into the hearing room with Barrett, who was wearing a black mask as she took her seat in the committee room.

ABC News’ Trish Turner

Judge Barrett, who has been diligent in keeping her mask on throughout the hearing, except for an occasional sip of water, removed it to be sworn in and to deliver her opening statement.

“As I said when I was nominated to serve as a justice, I am used to being in a group of nine -- my family," Barrett began. "Nothing is more important to me, and I am so proud to have them behind me."

Barrett said she'd bring new perspectives to the bench as she'd be the first mother of school-age children to serve, the first justice from the Seventh Circuit in 45 years and the only sitting justice who didn’t attend Harvard or Yale law schools.

After speaking of her own upbringing and family of nine, Barrett turned to how she interprets the law, following in the textualist and originalist approach of Justice Antonin Scalia, for whom she clerked. "It was the content of Justice Scalia's reasoning that shaped me. His judicial philosophy was straightforward: 'A judge must apply the law as it is written, not as she wishes it were,'" she said.

“Justice Scalia taught me more than just law. He was devoted to his family, resolute in his beliefs, and fearless of criticism. And as I embarked on my own legal career, I resolved to maintain that same perspective,” she said. “I worked hard as a lawyer and a professor; I owed that to my clients, my students, and myself. But I never let the law define my identity or crowd out the rest of my life.”

Barrett said a similar principle of separation applies to the role of the courts, a line that will likely pick up traction in questioning from Democrats.

“The policy decisions and value judgments of government must be made by the political branches elected by and accountable to the people. The public should not expect courts to do so, and courts should not try,” she said.

Invoking her children, Barrett described the standards she says she sets for herself on ruling in any court, another line Democrats will likely seize on in their arguments for upholding the Affordable Care Act.

“When I write an opinion resolving a case, I read every word from the perspective of the losing party. I ask myself how would I view the decision if one of my children was the party I was ruling against: Even though I would not like the result, would I understand that the decision was fairly reasoned and grounded in the law?” she said.

Barrett said she never sought out the Supreme Court nomination and thought carefully before accepting, acknowledging she will never take the place of Justice Ginsburg.

“I have been nominated to fill Justice Ginsburg’s seat, but no one will ever take her place. I will be forever grateful for the path she marked and the life she led,” she said.