Aaron Bernstein / Reuters

The presidential bids of Senators Kamala Harris, Amy Klobuchar, and Cory Booker haven’t exactly caught fire yet.

All of them are lagging behind in primary polls, struggling to break through in a race that has thus far been dominated by Joe Biden, Bernie Sanders, and the unlikely burst of South Bend, Indiana, Mayor Pete Buttigieg.

But luckily for Harris, Klobuchar, and Booker, they all sit on the Senate Judiciary Committee, a perch that affords them input on major nominations and a high-profile opportunity to participate in Congress’s response to Special Counsel Robert Mueller’s report on Russian interference in the 2016 election and whether President Donald Trump obstructed justice. On Wednesday, that meant they each had a nationally televised moment—seven minutes, to be exact—to question, talk over, or simply beat up on Attorney General William Barr for the benefit of their presidential aspirations.

Yet only Harris really took advantage. The first-term California senator—herself a former attorney general, of the nation’s most populous state—brought her skills as a prosecutor to bear as she questioned Barr about his handling of Mueller’s report.

As any casual C-SPAN viewer knows, lawmakers rarely make the most of their opportunity to question high-ranking government officials about the decisions they make on behalf of their constituents. Grandstanding is rampant, and politicians often end up using the precious few minutes they’re allotted to make speeches or merely harangue witnesses instead of trying to elicit useful information or advance a policy debate. Some barely get around to asking a question at all.

Klobuchar spent the first half of her seven minutes on Wednesday touting her own legislation, co-sponsored with Republican Senator James Lankford of Oklahoma, to boost the security of American elections. She then pivoted to questioning Barr about why he concluded that Trump’s request of White House counsel Don McGahn to remove Mueller as special counsel did not amount to obstruction of justice. Her performance seemed politically effective; she promoted her own bipartisan efforts on election security while simultaneously asking relevant questions of the attorney general. But Klobuchar broke no new ground, nor did she when she had a few extra minutes toward the end of the hearing.

Booker also began with a big chunk of throat clearing before he got around to asking Barr a question. He focused on Barr’s statement that the American public should “be grateful” that Mueller could find no evidence that the Trump campaign conspired with Russia to influence the election. Booker took exception to that, pointing to findings by Mueller’s team that Trump’s son Donald Trump Jr. was eager to meet with the Russians, even if he did not criminally conspire with them. But Booker’s line of questioning was hard to follow, and he lost time when he misspoke at one point and said “obstruction” when he meant “collusion.”

“I’m not sure what you’re talking about,” Barr told him. The senator had failed to land a blow.

Harris, by contrast, dispensed with any speechifying. She has said that, as the Democratic nominee, she would “prosecute the case” against the president. And on Wednesday, she set about to prove it. As has been her standard practice with Trump nominees and administration officials, she launched right into her questions as if she were cross-examining a witness. As the most junior Democrat on the committee, she was the last of 10 to question Barr. But she covered terrain that no one else had, and an attorney general whose slipperiness and legalistic hairsplitting had frustrated Democrats for several hours finally appeared to be caught off guard.

“Attorney General Barr, has the president or anyone at the White House ever asked or suggested that you open an investigation of anyone?” Harris began. “Yes or no?”

Barr briefly stammered.

“Could you repeat the question?” he asked.

Ultimately, the attorney general said no one had directly asked him to open an investigation, but he allowed that the topic had come up. “I’m trying to grapple with the word suggest,” he told Harris. “I mean, there have been discussions of matters out there that they have not asked me to open an investigation, but …”

The question was relevant, given Trump’s habit of using his Twitter account to demand that Barr’s predecessor, Jeff Sessions, launch inquiries of Hillary Clinton and other Democrats who have criticized him. Her point apparently made, Harris moved on to the Mueller report. She asked the attorney general whether he had reviewed the underlying evidence Mueller’s team had compiled before he reached his conclusion that the president would not be charged with a crime.

Barr said that he had not, and neither had Deputy Attorney General Rod Rosenstein, who had previously overseen the Mueller probe, after Sessions recused himself. “We accepted the statements in the report as factual record,” he said. “We did not go underneath it to see whether or not they were accurate.”

Harris seemed to anticipate Barr’s answer, and pounced. “As the attorney general of the United States, you run the United States Department of Justice,” she began. “If, in any U.S. attorney’s office around the country, the head of that office, when being asked to make a critical decision about—in this case—the person who holds the highest office in the land, and whether or not that person committed a crime, would you accept them recommending a charging decision to you, if they had not reviewed the evidence?”

Barr tried to pass the decision off to Mueller, but Harris stopped him. “You made the decision not to charge him,” she declared.

Harris then questioned whether Rosenstein’s involvement in the decision was ethical, given that the report documented how he was also a witness in the firing of FBI Director James Comey—an incident Mueller investigated for possible obstruction of justice. She asked Barr whether Rosenstein had been cleared by career officials in the department’s ethics office of potential conflicts of interest. Barr again seemed flustered, at one point turning around to aides to consult on his answer. Rosenstein was cleared of a conflict before Barr’s arrival in February, the attorney general eventually replied.

Soon Harris’s time was up. She left the hearing soon after and called on Barr to resign. She won raves from Trump critics on Twitter who were frustrated by her Democratic colleagues’ inability to puncture Barr’s legal arguments. By late afternoon, she had sent out a fundraising email to capitalize on her performance.

Granted, Harris’s success on Wednesday was more style than substance; the revelations she elicited from Barr were noteworthy, but they weren’t exactly bombshells that will change Trump’s political fortunes. Nor did her questioning reveal much about what kind of president she’d be compared with Klobuchar or Booker, or any of her other rivals. The job of president is not that of a prosecutor or a senator.

But the crucible of presidential politics is mostly performative; more to the point, it’s a series of performances over many months, where voters can see how candidates handle pressure, how they seize or miss opportunities, how they use their intellect, how they debate and confront opponents. There will be plenty more of them before Democrats make their choice next year, and Barr’s testimony about the Mueller report, in all likelihood, will turn out to be a blip on that long road.

But Harris had seven minutes on Wednesday to show what she could do, and she seemed to make the most of it.

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