He publicly released 12 pages of emails sent by Supreme Court nominee Brett Kavanaugh dealing with racial inequality. The documents were marked "committee confidential" -- meaning that only members of the Senate Judiciary Committee (which includes Booker) could have access to them.

"I understand the penalty comes with potential ousting from the Senate," Booker said in making clear he planned to break the rules. "I openly invite and accept the consequences of my team releasing that email right now."

To be clear: Booker isn't releasing these emails out of the goodness of his heart or solely because he thinks transparency is critically important when voting on a Supreme Court justice. That may well be part of his calculations. But the politics of all of this also plays a large part.

Asked afterward about his decision to open himself up to possible expulsion from the Senate, Booker made his motivations quite clear:

"A senior senator who is in leadership, I think he's the number two in leadership has, in effect, called for my expulsion from the United States Senate and and again I just say, 'Bring it.' If he wants to go through that process I fully accept responsibility for what I have done, and again I'm new in this place. This senator has been around a long time. He's in leadership. I think he was just like a lot of bullies are, a lot of talk and no action. And so let's see what he does. I'm willing to accept responsibility for my actions, but I don't know what, I don't know what that senior senator will do."

Booker is talking here about Texas Sen. John Cornyn who is, indeed the second-ranking Republican in the Senate. Cornyn was particularly exercised about Booker's decision, telling the committee that "running for president is no excuse for violating the rules of the Senate. ... This is no different from the senator deciding to release classified information. ... That is irresponsible and outrageous."

Cornyn is, without question, right about one thing: Booker is very likely running for president. And this decision to break the rules is a calculated one aimed at demonstrating that the New Jersey Democrat knows how to fight dirty -- and is willing to do just that against President Donald Trump.

Go back and read that full quote above from Booker. Change the "he" from Cornyn to Trump. Still works, right?

"I just say, 'Bring it.'" ... "I think he was just like a lot of bullies are, a lot of talk and no action."

That's not by accident. Booker, as well as Sen. Kamala Harris (D-Calif.), who made her own moment in a clash with Kavanaugh over the special counsel probe being run by Robert Mueller, and Sen. Amy Klobuchar (D-Minn.) all understand that they are on a very big stage right now. All politics is, in part, performance.

But running for president relies more on performance than running for any other office. Anyone who has ever considered running for the nation's top office knows that you need to be "on" in the big moments, show what you are made of when the people are watching.

And Democratic base voters are VERY much watching this Kavanaugh hearing.

They view Trump's decision to nominate a solid conservative for the seat of swing vote Justice Anthony Kennedy as only the latest in a series of massive affronts committed by Republicans, beginning with their total refusal to even meet with Merrick Garland -- President Barack Obama's nominee to replace the late Antonin Scalia on the court. More than 140 people have been arrested for protesting the Kavanaugh hearing on Capitol Hill over the first two days of hearings.

Booker knows that one of the biggest complaints from that base about the 2016 election was that Hillary Clinton simply played too nice with Trump. She and her campaign tried to stay within the established rules of a campaign. Trump refused to even acknowledge there were any rules. Clinton, in the mind of the Democratic base, was fighting with one hand tied behind her back. She would never "go there" on Trump because she and her team believed that getting down in the mud with Trump was a losing proposition -- not to mention those sorts of tactics might do real damage to the health of our political process.

Trump had no such concerns. He said and did whatever he believed it took to win. He brought a group of women who had accused Bill Clinton of sexual misconduct and sat them in the front row of a presidential debate with Hillary Clinton. He promised he would prosecute her if he was elected president. He suggested, repeatedly, that her health was failing and that she was simply not up to the demands of the job of president.

He broke, literally, every rule. Did so with relish. And won.

Which brings us to the positioning of Democrats for 2020 -- and what 2018 has taught us about the state of the party. Democratic base voters want not just liberals, but fighters . Alexandria Ocasio-Cortez rather than Joe Crowley. Andrew Gillum rather than Gwen Graham. Ayanna Pressley instead of Michael Capuano. They want someone who will take the fight to Republicans -- and to Trump in particular. Someone who will stand toe-to-toe with Trump and tell him, to his face, why he deserves to be impeached. Someone not afraid of, well, getting some mud on their shoes.

Republicans pushed hard on the idea that Booker was not just grandstanding in advance of 2020, but was doing so under false pretenses. Judiciary Committee Chairman Chuck Grassley's office insisted the documents that Booker made such a show of releasing on Thursday morning had in fact been cleared to be released earlier in the day. Booker's office responded by taking a victory lap, insisting that he had "shame[d] the committee into agreeing to make last night's documents publicly available."

Who has the right in this is hard to tell amid the spin -- and the possibility of miscommunication and mixed signals. But make no mistake: Booker got what he wanted here. Democratic activists won't care about the timing of the release of the documents. They will remember Booker staring down the Republican Senate majority and President Trump. Remember, presidential politics is, at times, a performance. And Booker gave this one his all.

What Booker did -- with clear intent -- on Thursday morning was to show he's not going to be cowed by the rules of the Senate. Or by a bully. He's going to say, "Bring it," and get ready to scrap.

UPDATE: This story has been updated with a response from Judiciary Committee Chairman Chuck Grassley's office, disputing Booker's portrayal of his document release as breaking the Senate's rules.