Barr, 68, previously served as attorney general in the early 1990s under President George H.W. Bush. Since then, he's worked as a corporate lawyer in private practice.
While Barr is widely-respected in the conservative legal world, some of his opinions have garnered controversy. Barr came under scrutiny for sending an unsolicited 20-page memo to the DOJ criticizing the Mueller probe's line of investigation into possible obstruction of justice and witness tampering by Trump.
The memo called Mueller's inquiry into whether Trump obstructed justice by when he fired FBI director James Comey "legally unsupportable" and "potentially disastrous."
Barr also said Trump's firing of Comey was "the right call," supported Trump's firing of Deputy AG Sally Yates, and expressed concern that special counsel Robert Mueller's team of prosecutors is biased against Democrats. As attorney general, he would oversee the Mueller probe.
Barr's previous comments around the Mueller probe combined with the high-stakes nature of the nomination, and hyperpartisan environment in Washington could lead to some tense clashes.
Conservative firebrand and Trump-allied Sen. Lindsey Graham, who made headlines for his angry attack on his colleagues during the Kavanaugh hearings, now leads the Committee.
Here are the key Senators to watch during Barr's confirmation hearings:
Newly-named Senate Judiciary Chairman Lindsey Graham
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"When you see Sotomayor and Kagan, tell them that Lindsey said hello because I voted for them. I would never do to them what you've done to this guy. This is the most unethical sham since I've been in politics," Graham said, referring to Obama-era nominees Sonia Sotomayor and Elena Kagan.
When Kavanaugh told Graham that he'd "been to hell and then some" over the allegations, Graham angrily responded, "This is not a job interview, this is hell."
Democratic Sen. Kamala Harris has been accused of hostility against Catholic judicial nominees and is laying the groundwork for a 2020 presidential campaign.
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Sens. Kamala Harris and Mazie Hirono (also a Democrat on the Judiciary Committee), have recently been accused of anti-Catholic bias for questioning whether judicial nominee Brian Buescher's membership in the Catholic fraternal organization Knights of Columbus would compromise his impartiality on the bench.
Barr himself is Roman Catholic, although not known to be a member of the Knights of Columbus.
As Harris embarks on a book tour ahead of a rumored presidential announcement sometime in late January, all eyes will be on whether she questions Barr's faith during the hearings, and whether she takes advantage of the spotlight to bolster her campaign ambitions.
Democratic Sen. Cory Booker of New Jersey is also reported to be mulling a presidential bid.
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During Kavanaugh's initial confirmation hearings, Booker took the dramatic step of threatening to release documents purportedly proving Kavanaugh supported racial profiling.
The comment was a reference to Stanley Kubrick's 1960 film "Spartacus" about an unsuccessful slave rebellion in ancient Rome.
Sen. Amy Klobuchar of Minnesota made headlines last September for her tough but measured cross-examination of Supreme Court Justice Brett Kavanaugh.
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Klobuchar, who worked as a district attorney before being elected to the Senate, was lauded for her incisive questioning of Kavanaugh and remaining cool and collected when he turned the questions back on her.
When she asked him to confirm his answer was no, he said "Yeah, and I'm curious if you have," to which she calmly responded, "I have no drinking problem, Judge."
The moment earned Klobuchar praise for her tough, but fair approach to questioning Kavanaugh and staying on topic as opposed to grandstanding.
After meeting with Barr on Thursday, Klobuchar told CNN's Anderson Cooper she intends to put the pressure on Barr in next week's hearings.
"I still have concerns relating to his expansive views on executive power & will push more at the confirmation hearing," Klobuchar wrote on Twitter . "He must promise to uphold the Mueller investigation."
Sen. Joni Ernst of Iowa is one of the first two Republican women to ever serve on the Committee.
While Ernst has no formal legal background, she served 23 years as a lieutenant colonel in the Iowa National Guard and three years as an Iowa state senator before becoming a US Senator.
Sen. Marsha Blackburn of Tennessee, a prominent Trump ally, is the other new Republican woman on the Committee.
Like Ernst, Blackburn is not trained as a lawyer, but she's worked in government for almost 25 years, beginning her career as director of the Tennessee Film, Entertainment, and Music Commission before being elected to the Tennessee state senate and eventually Congress.
Republican Sen. Josh Hawley of Missouri is the former attorney general of Missouri and the youngest currently-serving US Senator.
AP Photo/Jeff Roberson, File
Hawley holds a JD from Yale Law School and has worked as a law clerk, an appellate litigator, a law professor, and served as Missouri's attorney general from 2017 until being sworn into the Senate in 2019.
Hawley is staunchly anti-abortion, and has called for "constitutionalist, pro-life judges" to be appointed to federal courts.
SEE ALSO: Republicans are worried about a 'Kavanaugh 2.0' scenario with Trump's attorney general nominee