Kavanaugh secured the needed votes on Friday, when Sen. Susan Collins, R-Maine, who had been one of a handful of officially undecided senators, announced she would vote "yes" on his confirmation.
"I can't understand how a woman could turn her back on other women," Shapiro said of Collins. "She’s a traitor, and we’ll vote her out in November."
Just before 1 p.m. ET, hundreds of protesters crossed police lines to gather on the steps of the Senate, chanting, "November is coming."
Some held large red signs with black letters, stretched across several steps that read, "We believe all survivors." Two women kneeled in front of the steps, fists raised in the air, before hundreds more protesters who gathered in front of the steps.
Within half an hour, police began climbing the steps and detaining protesters. As they were brought off the steps, officers zip-tied protesters' hands behind their backs before leading them away from the building.
U.S. Capitol Police said a total of 164 people were arrested during the protests for "crowding, obstructing, or incommoding." Police said the people who were arrested were being processed offsite and would then be released.
Simultaneous protests took place in cities across the United States, including Denver, Atlanta, Cleveland and New York City.
In Austin, Texas, protesters blocked a bridge in a demonstration against the Kavanaugh confirmation, and police arrested protesters after they refused to move, NBC affiliate KXAN reported.
In New York City, marchers hit the streets Saturday night, some holding a banner that read "No Justice No Seat." The group made their way to Times Square, where they chanted in opposition to Kavanaugh and in support of abortion rights and other issues. In Topeka, Kansas, a crowd of demonstrators protested outside a venue before President Donald Trump was to speak at a rally.
Earlier in the day at the Capitol, as protesters gathered, some carried signs quoting Dr. Christine Blasey Ford, the psychology professor at Palo Alto University who alleged that Kavanuagh sexually assaulted her in high school.
"I am here because I believe it is my civic duty," one sign proclaimed, quoting Ford.
Other signs referenced testimony given by Kavanaugh in response to Ford's allegations.
“If only he liked women as much as he liked beer,” another woman's sign read, referring to Kavanaugh's testimony before the Senate that he likes beer.
Large swaths of protesters on the Hill echoed alternating chants of, "I believe Christine Ford," and "I believe Anita Hill," the woman who accused Supreme Court Justice Clarence Thomas of sexual harassment before his confirmation hearing in 1991.
One of the women who accused Kavanaugh of sexual misconduct during his time at Yale University, Deborah Ramirez, said in a statement Saturday that the senators discussing the impending vote on the Senate floor brought her back to the moment of the alleged misconduct.
"As I watch many of the Senators speak and vote on the floor of the Senate I feel like I'm right back at Yale where half the room is laughing and looking the other way. Only this time, instead of drunk college kids, it is U.S. Senators who are deliberately ignoring his behavior," Ramirez said. "This is how victims are isolated and silenced."
Ana Maria Archila — the woman who confronted Flake in an elevator with her sexual assault account — told MSNBC's Joy Reid on Saturday that Flake and Collins had failed their constituents.
"We deserve elected officials who understand that their role is primarily to govern by listening," Archila said.
Before the vote, President Trump tweeted that there were protesters among the crowd in favor of Kavanaugh, suggesting without evidence that some protesters against Kavanaugh had been paid to be there.
"Women for Kavanaugh, and many others who support this very good man, are gathering all over Capitol Hill in preparation for a 3-5 P.M. VOTE. It is a beautiful thing to see - and they are not paid professional protesters who are handed expensive signs. Big day for America!" Trump wrote.
One woman in favor of Kavanaugh, Annabelle Rutledge, told MSNBC that her heart went out to Ford and that she believed something traumatic happened to her, but added that Kavanaugh's confirmation could not be stymied by "uncorroborated" allegations.
"She has the right to tell her story but she doesn’t have the right to start a smear campaign when there's no proof," Rutledge said.