Ranking Member Chuck Grassley of Iowa, the top Republican on the Senate Judiciary Committee, complained that the committee hasn't received all of the records Republicans originally sought from Jackson's time on the sentencing commission but offered a bit of praise.

"We're off to a good start," Grassley said, comparing Jackson's hearings against those for Justice Brett Kavanaugh.

As senators have used Supreme Court confirmation hearings in recent years for political grandstanding, Grassley also reminded the committee of its purpose.

"In any Supreme Court nomination, the most important thing we look for is the nominee's view of the law, judicial philosophy and view on the role of a judge. I'll be looking to see whether Judge Jackson is committed to the Constitution as originally understood," he said.

-ABC News' Trish Turner

After drawing a contrast between America of the past and present, from a nation that once had hundreds of thousands of enslaved people to that of a "more perfect union," Senate Judiciary Chairman Dick Durbin, D-Ill., defended Jackson against concerns voiced by Minority Leader Mitch McConnell and some other Republicans that, as a former public defender, she will have "special empathy" as some Democrats touted.

"The cameras and the lights here today can make it easy to forget that at its core the responsibility you seek is one of service -- and I'm fully confident you'll serve Americans from all walks of life, all backgrounds fairly and faithfully," Durbin said. "Now there may be some who claim without a shred of evidence that you'll be a rubber stamp for this president. For those would-be critics, I have four words: Look at the record," he added.

Pointing out that the committee has already scoured her records now on four different occasions and seen "every published and reported word you've written or spoken," Durbin said, "For those who say they need more, I would answer that you've sat down personally with every member of the dais of the committee, Democrats and Republicans."

In what's likely to become a theme for Democrats, Sen. Patrick Leahy, D-Vt., echoed Durbin's defense.

"Judge Jackson is not anti-law enforcement. She hails from a law enforcement family. She's also won the support of preeminent national law enforcement organizations including the national fraternal order of police," Leahy said. "And no, she's not soft on crime. Her background as a federal public defender would bring an informed perspective of our criminal justice system to the Supreme Court."

In a show of support for his nominee, Biden tweeted a video from Judge Jackson's nomination ceremony at the White House ahead of her confirmation hearings Monday.

"Judge Ketanji Brown Jackson is a brilliant legal mind with the utmost character and integrity," the tweet read. "She deserves to be confirmed as the next Justice of the Supreme Court."

Democrats, with 50 seats in the Senate and Vice President Kamala Harris as a tie-breaking vote, already have the votes to confirm Jackson, but the White House is hoping to secure Republican votes and the approval of the American public with this week's hearings.

Senate Judiciary Chairman Dick Durbin, D-Ill., gaveled in the hearings at 11:02 a.m. -- marking the first time in 233 years that the Senate will consider the nomination of a Black woman to the Supreme Court.

"The rule of law has stood the test of time, but the reality is that the court's members have never really reflected the nation they served,'' Durbin said.

"Today is a proud day for America," he continued, noting he saw many young African American women on the steps of the Supreme Court at a rally for Jackson's confirmation earlier this morning.

Durbin also had a preemptive message for Republicans on the committee like Missouri Sen. Josh Hawley, who are expected to attack Jackson's credibility, noting that she's been vetted three times by the Senate and confirmed.

"Despite your record, we've heard claims that you're, quote, soft on crime. These baseless charges are unfair," he said.

"You, Judge Jackson, are one of Mr. Lincoln's living witnesses of an America that is unafraid of challenge, willing to risk change, confident of the basic goodness of our citizens -- and you are living witness to the fact that in America all is possible."