Beyond the protesting spectators and U.S. senators quarreling over access to documents, Senate Judiciary Republicans and Democrats revealed Tuesday the contentious issues that will be fought over as Brett Kavanaugh's confirmation hearing to the U.S. Supreme Court heads into its second day.

Kavanaugh sat stone-faced throughout much of Tuesday's hearing, as senators from both sides sparred over the merits of his nomination. He only occasionally cracked a smile. There were no head nods, no eye rolls. Kavanaugh choked up at the end of his opening statement, in which he vowed to keep an open mind in every case that might come before him on the Supreme Court.

The significant political and legal stakes in the nomination were repeated time and again by senators of both parties, and expect to hear more on that Wednesday when Kavanaugh is asked to respond to questions about Supreme Court precedent, his views on executive power and the independence of the judiciary. Here's a snapshot of what we've learned so far and what is likely ahead as Kavanaugh, a federal appeals judge, moves closer to elevation to the high court.

>> President Donald Trump. The elephant in the hearing room isn't just Republican senators' party symbol. It's Trump. The Republican perspective: Opposition to Kavanaugh isn't about his qualifications or over access to documents. It's an attempt, rather, “to relitigate the 2016 presidential election,” according to Sen. Ted Cruz, R-Texas, and Sen. Mike Crapo, R-Idaho. From the Democrats' perspective: “Overall, you [Kavanaugh] are the nomination of Donald Trump,” said Sen. Richard Durbin, D-Illinois. Trump is “contemptuous of the rule of law,” someone who “harasses the attorney general of the United States almost on a daily basis,” and “you are the person he wants on the Supreme Court.” Two senators read aloud a recent tweet from Trump that sarcastically said “Thanks, Jeff” for moving forward on the prosecutions of two Republican lawmakers just weeks away from the midterm elections.

>> How Kavanaugh will vote. When the questioning of Kavanaugh begins Wednesday, Democratic senators will press him on his D.C. Circuit decisions and his views on a range of issues—including abortion, net neutrality, firearms, voting rights, labor issues, campaign finance and federal regulations. Kavanaugh's opinions and writing will go under a microscope. Expect a healthy debate over what it means when a nominee says an issue is “settled.” The Supreme Court, of course, can unsettle anything it wants. Republicans will find cases that they will say buck the argument that Kavanaugh only rules for businesses and against employees, or that he only rules for prosecutors. “A judge must be independent and must interpret the law, not make the law. A judge must interpret statutes as written. A judge must interpret the Constitution as written, informed by history and tradition and precedent,” Kavanaugh said in his opening statement.

>> Documents and more documents. Expect to hear Democrats keep hitting this drum. A Monday-night dump of 42,000 Kavanaugh-related documents on the Senate Judiciary Committee fueled Democratic senators' argument that they haven't seen the full universe of records from Kavanaugh's time inside the George W. Bush White House. Sen. Richard Blumenthal, D-Connecticut, tried unsuccessfully to adjourn the hearings until the latest documents could be reviewed. Blumenthal said Kavanaugh will forever have an asterisk next to his name—”appointed by a president named as an unindicted co-conspirator after the vast majority of documents relating to the most instructive point of his life were concealed. The question will always be—why? Why was all that material concealed?” Republicans counter that Democrats have a large universe of records from which to weigh Kavanaugh's nomination. Judiciary Chairman Chuck Grassley, touting the release of hundreds of thousands of records, contends the Kavanaugh nomination has been “the most transparent” process yet for a Supreme Court nominee.

>> Kavanaugh as the good guy. Republican senators on Tuesday began the process of “humanizing” Kavanaugh and will continue to introduce the nominee who is a father, basketball coach, employer of female clerks and more. They also stress his academic qualifications and judicial experience, his respect for precedent and his faithfulness to the text of congressionally enacted statutes. Expect to hear Republicans push back against claims Kavanaugh is outside of the mainstream on certain issues. Several Republicans in their opening remarks Tuesday pointed to liberal support for Kavanaugh—including praise from Arnold & Porter's Lisa Blatt, who introduced Kavanaugh, and from Akhil Amar, a Yale Law School professor who taught Kavanaugh. Amar is among those who are expected to testify later this week.