Sen. Bernie Sanders (I-Vt.) speaks to a Pittsburgh crowd about health-care on Saturday. (Jeff Swensen for The Washington Post)

Sen. Bernie Sanders took the stage and got right to it, warning 2,200-odd Ohioans that their lives are at risk if Senate Republicans push through their health-care bill.

“Put yourself into someone else’s shoes,” Sanders (I-Vt.) said Sunday at Columbus’s ExpressLive concert hall, where large screens that usually play bar specials were showing CBO scores. “What does it mean today if you are struggling for your life, dealing with cancer, dealing with heart disease, dealing with diabetes, dealing with some chronic illness threatening your existence? What does it mean when you read in the paper that Republicans might take away your insurance?”

A voice in the audience shouted out the answer: “You die!”

“I say this not to be overly dramatic,” Sanders said. “If you take away health care from 23 million people, what will happen? People will die, by the thousands!”

The Columbus rally, the largest of three that Sanders staged over the weekend in Rust Belt states that Donald Trump won in 2016, was part of an aggressive, last-ditch push to stop the Senate bill. Last week, protesters packed Reagan National Airport to hector Republicans before they went home for the weekend. And a pro-Trump super PAC that bought ads to pressure Sen. Dean Heller (R-Nev.) found that AARP had been waging an air war against Heller for months — from the other side.

(Monica Akhtar/The Washington Post)

Sanders, who wants Democrats to delay any vote on the bill past the July 4 recess — allowing more time for voter information, and more protests — is the one member of the Democratic caucus capable of pulling together big crowds in a hurry.

Teeing up the week’s votes this way makes a point — they are unlikely to be able to tack their rhetoric into the legislation itself. But it also reveals the limitations of what Democrats, who have taken to Twitter to oppose the bill and plan to offer amendments to alter it, can do to stop a bill in the Republican-controlled chamber.

“You have to do your best to tell the truth, but at the same time you have to make it clear that violence of any kind is unacceptable,” Sanders said in an interview at a dinner stop between Pittsburgh and Columbus. “It’s not me who’s saying people are dying. They will. That’s just a fact. You have Harvard University making that statement. And it’s common sense — of course people are going to die. It doesn’t give me any pleasure to say that Trump is a pathological liar. It’s just the truth. I’ve never called any other politicians pathological liars.”

That tone, shared increasingly by Democrats, comes after a run of special elections that the party failed to turn into referendums on the GOP health-care bills. In particular, the June 20 defeat of Jon Ossoff, the highly touted (and first-time) Democratic candidate who narrowly lost a Georgia race to replace now-Health and Human Services Secretary Tom Price in the House, has bolstered left-wing Democrats — not only to press harder for a win but also to insist on more liberal candidates.

Ossoff pointedly told voters that he would oppose the GOP’s health-care bill but would stop short of expanding Medicare.

Reid Goldberg, a 26-year old political strategist who showed up at Sanders’s Pittsburgh rally with gear from defeated Montana candidate Rob Quist, groused about how Democrats had invested too little in the left-wing country singer’s race, instead pouring millions into Ossoff’s.

“I remember thinking: ‘If you guys think that’s the one you can win, you better f---ing win,’ ” Goldberg said. “They lost.”

Adrian Luther, 26, of Greensburg, Pa., listens to Sen. Bernie Sanders (I-Vt.) speak Saturday in Pittsburgh. (Jeff Swensen for The Washington Post)

John Fetterman, the mayor of a town near Pittsburgh who became a high-profile Sanders supporter, argued that the race proved the need for Democrats to run bold.

“I don’t know why we don’t have the stones to do the same thing Republicans do when we’re the ones taking the moral position,” Fetterman said. “Health care is a right. If Republicans can get behind something that’s at 16 percent support, what are we doing when we spend $35 million on a losing guy in Georgia who was afraid to run on single payer and was afraid to make the super-rich pay enough in taxes? You run on what’s right.”

The Sanders tour tested that theory, carried out by a politician who still has high favorability ratings — unlike the leaders of the Democratic Party. His dinner Friday night, in territory that had voted solidly for Trump, was interrupted six times by well-wishers who recognized him and wanted photos. One asked him to reconsider his position on abortion (“think of the babies”) before saying he had impressed her with his bluntness. Others asked him to run for president again.

Sanders’s tour wasn’t the only sign of action against the Senate health bill., which used the weekend rallies to sign up thousands of new activists, is asking anyone who can to get to Washington to join a human chain around the Capitol on Wednesday. Even the Democratic Socialists of America, which is often critical of congressional Democrats and generally favors single-payer health care, planned daily marches to protest the Republican bill.

The Indivisible network of protest groups has been staging protests in key senators’ home states and encouraging activists to call senators to demand “no” votes. It has also produced two online hubs to help shape the response: TrumpCare Ten, naming the Republican senators seen as the most likely to respond to pressure against the bill, and Our Amendments, a project encouraging Democrats to introduce as many germane amendments to the bill as possible if they get the chance to slow it down.

On the tour, crowds listened raptly at each stop as MoveOn’s Washington director, Ben Wikler, warned that zero hour was coming on the bill and tried out chants. In Pittsburgh, one of the chants — calling out Sen. Patrick J. Toomey (R-Pa.) — tested the limits of the crowd: “Senator Toomey, here’s what you don’t get! If you pass this bill, we’ll never forget!”

In each city, signs or slogans that targeted the president were relatively rare — there was readier anger at the Republicans in Congress who had shaped the Senate health-care bill. Many in the crowd said the president seemed to be ignorant or blase about it. Instead, even before activists or local people with health-care horror stories took the stage, they gossiped about the drafting of the bill — the Better Care Reconciliation Act — itself.

“The process scares the crap out of me,” said Cathy Coyne, 51, who formed an Indivisible group with friends in a suburb of Pittsburgh. “They did it all behind close doors — 12 men, no women.”

In Pennsylvania and Ohio, where many rural voters who had twice backed Barack Obama went for Trump in 2016, Democrats hope that incumbent Republicans who vote for the health-care bill will become infamous on their own.

“The ACA’s been good for Ohio, and Rob Portman knows it,” said David Pepper, the chairman of the state’s Democrats. “We’ve got a Republican governor, John Kasich, who has said again and again that it’s working.”

The events in Pennsylvania, Ohio and West Virginia were the first big rallies since a man who once volunteered for Sanders’s presidential campaign opened fire on Rep. Steve Scalise (R-La.) and other Republicans in Alexandria, Va.

In the short term, Sanders and Democrats said that voters could pressure their Republican senators to vote against the bill. It was a “resistance” strategy with fewer tools than the 2009-2010 tea party blockade of the ACA itself. Few Republicans are holding open public events, especially in the wake of the Scalise shooting.

The GOP’s quick-shot process offered no hearings to protest. Almost as importantly, it has led to little media coverage of the bill through June, with local newspapers and TV stations offering little information on what the bill contains.

Mike Mikus, a Democratic strategist who in 2010 helped buck the tide against Democrats in the increasingly conservative rural counties outside Pittsburgh, argues that the party’s demographic slide could be reversed by running against the bill.

In 2012, after a redistricting, Rep. Mark S. Critz (D-Pa.) narrowly lost reelection to a Republican. But lost in that outcome, Mikus said, was the fact that Critz ran 22,000 votes ahead of the Obama-Biden ticket that year, branding himself as a “Democrat for jobs” who would protect Medicare.

Trump embraced a similar message in 2016 but signed off on the cuts favored by Republicans in Congress.

“Trump promised people better health care for less money; Paul D. Ryan never promised them that,” Mikus said. “I think he can be their Nancy Pelosi in very short order here.”

Sanders was focused on more than the health-care vote and the 2018 election. At each stop, he repeated his call for “Medicare for all” to replace the existing health-care system-- and at each stop, he got loud cheers. When the Republicans’ health-care fight ends, with passage or failure, Sanders intends to release a single-payer bill that could take the place of the House legislation as a rallying point for Democrats and activists.

The special elections, he said, had proved the need to go large. “Democrats have to meet people where they are,” he said, pointing to polling that showed support for a “single payer” concept ticking up, even after California — and his own Vermont — bottled single-payer bills over worries about cost. The larger worry, about the Senate health-care bill and about 2018, was that Republicans had enough money to stop a backlash.

“My sense is that the Republicans understand that this bill is a disaster,” Sanders said. “You can’t throw 23 million people off health insurance, give tax breaks to millionaires and not know it’s a disaster. But I think what they believe is that with the Koch brothers, and with unlimited amounts of money, they will be able to survive. What Citizens United has done is change the dynamics of American politics so that anybody who runs against any of these incumbents will see massive amounts of personal attacks from Day One.”

Ed O’Keefe in Washington contributed to this report.