By Stephen Collinson, Betsy Klein and Abby Phillip, CNN

(CNN) — Senate Democrats disrupted the start of the Judiciary Committee hearing of Supreme Court nominee Brett Kavanaugh Tuesday morning.

Sens. Cory Booker, Richard Blumenthal, Kamala Harris and others interrupted Judiciary Chairman Chuck Grassley’s attempt to launch the hearing, repeatedly decrying what they say are missing documents and emails from Kavanaugh’s time as a White House lawyer from stacks released this summer. An additional 42,000 documents were released Monday night.

President Donald Trump’s second Supreme Court nominee is poised to succeed swing vote Justice Anthony Kennedy, the conservative-centrist who joined with liberals in some key decisions to uphold abortion rights. Kennedy was also the decisive vote for same-sex marriage and university affirmative action.

The theatrics reflect the impotence of Democrats who lack the votes in the Senate to block Kavanaugh’s confirmation. It is not even certain all Democrats will stick together since endangered liberal senators up for re-election in red states are under intense pressure to back the confirmation.

When Grassley pressed on, speaking over Harris, her objection was reinforced by interventions from other Democrats, in a choreographed show of dissent from Democrats under fierce pressure from their grassroots voters to disrupt Kavanaugh’s likely confirmation.

“What are we trying to hide, why are we rushing?” Vermont Sen. Patrick Leahy asked.

But Grassley denied Democratic attempts to get a vote in the committee on whether to adjourn the hearing, and complaints that the late arrival of the documents and other controversies flew in the face of committee rules and basic fairness.

“Maybe it is not going exactly the way the minority would like it to go, we have said for a long period of time that we are going to proceed on this very day,” Grassley said.

In the public gallery, protestors started shouting before they were removed by Capitol Hill police officers, adding to an atmosphere of chaos and recrimination around the hearing.

Kavanaugh watched the arguments in the committee with a bemused look on his face.

A ‘pro-law judge’

When he does begin testifying Tuesday, Kavanaugh, in his first major test as a Supreme Court nominee on Capitol Hill, is expected to tell senators that he is a “pro-law judge.”

“A good judge must be an umpire — a neutral and impartial arbiter who favors no litigant or policy,” he will say, according to excerpts of his prepared remarks. “I don’t decide cases based on personal or policy preferences. I am not a pro-plaintiff or pro-defendant judge. I am not a pro-prosecution or pro-defense judge. I am a pro-law judge.”

Likening a judge to an umpire could be a reference to Chief Justice John Roberts’ confirmation hearing back in 2005, when he said his “job is to call balls and strikes and not to pitch or bat.”

“To me, Justice Kennedy is a mentor, a friend, and a hero. As a Member of the Court, he was a model of civility and collegiality. He fiercely defended the independence of the Judiciary. And he was a champion of liberty,” Kavanaugh will say, per the excerpts.

Kavanaugh, currently a circuit judge on the United States Court of Appeals for the District of Columbia Circuit, will also praise his colleague Judge Merrick Garland, President Barack Obama’s unsuccessful Supreme Court nominee.

“I have served with 17 other judges, each of them a colleague and a friend, on a court now led by our superb chief judge, Merrick Garland,” the prepared remarks say.

Controversy over documents

Ahead of Tuesday’s hearing, the first of a week of confirmation hearings for the nominee, committee Democrats criticized the Trump administration for holding back documents related to Kavanaugh’s service in the George W. Bush White House. The administration held back more than 100,000 pages of documents related to his service because the White House and the Department of Justice have determined they are protected by constitutional privilege, according to a letter to the Senate Judiciary Committee.

On the eve of the hearing Monday night, the Senate was given an additional 42,000 pages of documents, prompting criticism from Senate Minority Leader Chuck Schumer. Grassley, a Republican, tweeted that his staff completed the review of “each and every one of these pages.”

Grassley is planning to talk broadly about the role of a judge and Kavanaugh’s qualifications during his opening remarks, a source familiar with the remarks told CNN. But Grassley will take significant time in his opening to explain the document process and to defend it.

Noting that Kavanaugh has more than 300 opinions and submitted around 17,000 pages with his committee questionnaire, Grassley is likely to stress that he’s released thousands of pages and that he’s only asked for non-privileged documents and that Democratic requests for every document would have taken months to complete.

A White House official said that Trump aides believe Democrats have made a strategic mistake by focusing on document production, an issue they believe has left Kavanaugh unscathed but has left Democratic lawmakers looking like they are fixated on a bureaucratic dispute.

Going into Tuesday’s hearing, White House aides believe their nominee’s task of introducing himself to the country hasn’t been made more difficult in the weeks leading up to this hearing. Kavanaugh will have an opportunity to introduce himself and his approach to the bench in his own words.

Kavanaugh has been prepping intensively in recent weeks but he held his last, full-day mock hearing last Monday, the White House aide said. Since then, he’s been doing mini-debate prep sessions at his home or in his chamber.

Some of the sessions have focused on making sure that he is comfortable “with people shouting him down” or being heckled by protesters.

“This isn’t his first rodeo,” said the official, who acknowledged that Kavanaugh has been a judge for 12 years and judges don’t often get interrupted or stopped mid-sentence. So advisers have put in a lot of time priming him for what is likely to be a contentious hearing.

The-CNN-Wire™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.