(CNN) Two Democratic senators weighing 2020 presidential bids are set to have a high-stakes tryout Wednesday in the confirmation hearing for President Donald Trump's Supreme Court nominee, Brett Kavanaugh.

Sens. Kamala Harris of California and Cory Booker of New Jersey are both on the Senate Judiciary Committee, which means they'll get their chances to grill Kavanaugh as senators begin asking him questions Wednesday.

They've been at the forefront of the broad Democratic opposition to the nominee, both trying Tuesday to delay the confirmation hearing with complaints that reams of Kavanaugh documents had not yet been examined. They also sent emails to their fundraising lists highlighting their opposition.

Harris, in her email, called Kavanaugh an ideologue "hand picked by special interest groups because of his opposition to Roe v. Wade," the 1973 decision that legalized abortion.

Booker's email cast Kavanaugh as a threat to special counsel Robert Mueller's investigation of Trump. "President Trump should not be able to handpick a judge who could effectively serve as his 'get-out-of-jail free' card," he said.

Their opposition is unlikely to slow Kavanaugh's march to confirmation. Republicans have 51 votes in the Senate, meaning the GOP can afford to lose one vote and still confirm Kavanaugh, with Vice President Mike Pence to break the tie. So far, no Republicans have broken ranks.

But it is an opportunity to demonstrate their styles and show how they would confront Trump's administration just months before high-profile Democrats are expected to begin launching their 2020 campaigns. Harris and Booker have traveled and fundraised extensively during this year's midterm election campaigns, laying the groundwork for presidential bids.

Sen. Lindsey Graham, a South Carolina Republican, chided ambitious Democrats for casting Kavanaugh as fulfilling a Trump anti-abortion litmus test, pointing to Hillary Clinton saying she'd choose Supreme Court justices who would uphold Roe v. Wade. "Anyone running for President over there, I dare you to disagree with her. You will wind up like I did, getting 1%," Graham said.

"You can't lose the election and pick judges," Graham said. "If you want to pick judges, you better win."

The confirmation hearing -- with Sen. Amy Klobuchar of Minnesota, another possible 2020 contender, also among the Democratic committee members -- is likely to showcase their different styles.

Harris, in particular, has won praise from progressives for her sharp questioning of Trump appointees in previous hearings.

The former California attorney general is the last member of the Senate Judiciary Committee to ask questions in hearings, as its most junior member. That gives Harris, who prepares extensively for the hearings, an opportunity to identify questions she believes the person testifying hasn't sufficiently answered -- and then pounce, serving as the closer for Democrats.

That's what happened with Gina Haspel, Trump's CIA director, in her May confirmation hearing before the Senate Intelligence Committee, of which Harris is also a member.

In the hearing, Harris asked Haspel whether the President George W. Bush-era techniques for interrogating terrorism suspects, like waterboarding, were immoral, and Haspel deflected. "Answer yes or no," Harris shot back.

She interrupted when Haspel tried to dodge the question. "Please answer, yes or no: Do you believe in hindsight that those techniques were immoral?"

Haspel deflected again, and Harris said, "Will you please answer the question?"

When Haspel said, "Senator, I think I've answered the question," Harris responded, "No, you've not."

Later, Sen. John McCain, an Arizona Republican, alluded to Harris' line of questioning when he announced his opposition to Haspel's nomination, saying, "Her refusal to acknowledge torture's immorality is disqualifying."

Stylistically, Booker tends to ask longer, bigger-picture questions than Harris does, though he's been part of key moments as well.

One such moment came in January, when he told Homeland Security Secretary Kirstjen Nielsen that her "silence and ... amnesia is complicity" when she denied hearing Trump refer to "s***hole countries" in a private meeting.

Even more prominently, in January 2017, Booker testified in front of the Senate Judiciary Committee, before he became a member of that panel, against Jeff Sessions' nomination for attorney general.

"Sen. Sessions has not demonstrated a commitment to a central requisite of the job: to aggressively pursue the congressional mandate of civil rights, equal rights and justice for all of our citizens," Booker said then.