'Start Here': Woodward's explosive book, testy Kavanaugh confirmation and social media companies on Capitol Hill. What you need to know to start your day.

It's Wednesday, Sept. 5, 2018. Here are some of the stories we're talking about on ABC News' new daily podcast, "Start Here."

1. White House denies 'fabricated stories' in Bob Woodward's new book

The White House is pushing back against explosive reporting by veteran D.C. journalist Bob Woodward in his new book about President Donald Trump, "Fear: Trump in the White House."

Excerpts published Wednesday in The Washington Post have Woodward painting a portrait of behind-the-scenes chaos and paranoia at the White House, including the president in one anecdote lashing out to aides about Attorney General Jeff Sessions, calling him a "traitor" and "mentally retarded."

White House press secretary Sarah Sanders said Woodward was told "fabricated stories, many by former disgruntled employees" that were designed "to make the President look bad."

ABC News Senior White House Correspondent Cecilia Vega says the White House could have trouble denying Woodward's reporting: "This is not a tabloid reporter. This is one of the most respected journalists. ... They're going to have a hard time going up head-to-head with him."

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2. Interruptions, protests color first day of Kavanaugh hearings

It took literally five seconds for the interruptions to begin during the first day of Brett Kavanaugh’s Supreme Court confirmation hearings. And they didn't stop.

Democrats asked to delay, saying they'd just gotten 42,000 pages of documents late Monday. And then the interruptions started coming from behind Kavanaugh, as protesters from various groups shouted as loud as they could, for as long as they could, before they were led out.

ABC News' Senior National Correspondent Terry Moran is covering these hearings and says he’s never seen a hearing like this one.

3. Silicon Valley goes to Washington: Facebook, Twitter execs face grilling

Tech leaders will be on Capitol Hill Wednesday to face questions from the Senate Intelligence Committee about foreign influence in U.S. elections. Twitter CEO Jack Dorsey and Facebook COO Sheryl Sandberg will be grilled by lawmakers next to an empty seat for Google founder Larry Page, who is not expected to attend.

"Congress wants to be reassured that these three companies are doing something to stop the kind of misinformation that ended up being so rampant in the previous election," ABC News' Zunaira Zaki, who covers tech and business, tells us.

4. Nike stands by Colin Kaepernick in new campaign

Nike marked the 30th anniversary of its slogan "Just do it" with Colin Kaepernick as the face of a new campaign. The decision to use the quarterback, who has remained unsigned since he became synonymous with kneeling during the national anthem, drew strong reactions online from both sides of the debate.

"There are going to be people who will not buy Nike products ever again," USA Today sports columnist and ABC News contributor Christine Brennan tells us. "But I have a feeling there's going to be a lot of people who are going to buy Nike for the first time because of this."