Around 7:30 pm on Monday, Sen. Cory Booker (D-NJ) and civil rights icon Rep. John Lewis (D-GA) walked alone from the House side of the US Capitol to the Capitol steps to discuss Senate Republicans’ health care bill.

Other senators, Capitol Hill staffers, and members of the public began to join them. About four hours later, what began as an impromptu get-together of two men had swelled to a 300-person strong rally at the Capitol — and perhaps the most dramatic demonstration of opposition to the Senate Republican health bill yet.

“If you have ever in your life been the father of a very sick child and didn’t have health insurance, you’ll never forget it as long as you live. I know it. I’ve been there,” said Sen. Dick Durbin (D-IL), the No. 2 ranking Senate Democrat.

The gathering came in the midst of efforts by resistance leaders to dramatize the extent of the public’s opposition to the bill. Left-wing activists believe that if they can draw enough public attention and scrutiny to the bill — which the Congressional Budget Office estimated would result in 22 million fewer Americans having health insurance — they can cow Republicans into not passing it. It only takes three Senate Republican defections for the bill to be defeated, and so far at least five have said they oppose it in its current form.

The video of the event on Monday is remarkable. Booker and Lewis meet on the House side of the Capitol, cross over to the Senate, and sit outside the Capitol. About 25 minutes in, a traffic engineer named Denai from New Jersey visiting the Capitol comes up to the members of Congress and tells them he has also has concerns about the bill.

Another family comes, and Sen. Chris Coons (D-DE) comes out on the steps as well. (“You conjured a great Delawarean,” Booker tells the tourists.) Sen. Chris Murphy (D-CT) arrives, and takes a turn holding Booker’s iPhone to stream it for a Facebook Live video. Also joining them soon after were key Senate Democrats: Senate Minority Leader Chuck Schumer (D-NY), Sen. Jeff Merkley (D-OR), Sen. Bob Casey (D-PA), Sen. Brian Schatz (D-HI), and Sen. Kirsten Gillibrand (D-NY).

Next, they’re joined by MoveOn’s Ben Wikler, organizers with UltraViolet, and Planned Parenthood activists. By the end, hundreds of people were chanting on Booker’s every word as organizers urged the crowd to reconvene for “the People’s Filibuster” (an action at the Capitol over health care from 2 to 7 pm on Tuesday) and for a “human chain” of linked arms that’s set to form around the Capitol building on Wednesday.

“Right now, the biggest obstacle we face is not [Republican senators], but the silence of those who could do something about it. Silence is the enemy. Apathy is the enemy. Indifference is the enemy,” Booker said as the event closed down at 11 pm. “We've already seen in the past election when too many stay home. We have seen the consequences of that too many times.”