In speeches and social media campaigns, the contrasts between Bernie Sanders and Hillary Clinton are coming into sharp focus just ahead of major nominating contests in a dozen states.

Sanders, who is leading in national polls but trailing in South Carolina, which holds its Democratic primary on Saturday, "unloaded" on Clinton in a speech to roughly 6,500 people at Chicago State University on Thursday evening, the Washington Post reported.

Amplifying the arguments he's made in recent days, Sanders "attacked Clinton for having accepted campaign contributions and speaking fees from Wall Street interests. And then he sharply criticized her support, as first lady and as a New York senator, of welfare reform, free trade, an anti-gay rights bill and the Iraq War—all measures he opposed during his long career in Congress," according to the Post, which described the remarks as "striking for both their length...and his tone."

Meanwhile, on Twitter Thursday, hashtags were employed to further draw distinctions between the candidates' records.

Piggybacking on Black Lives Matter activist Ashley Williams' #WhichHillary hashtag—which was written at the bottom of a banner Williams held up while calling Clinton out for hypocrisy on racial and criminal justice at a fundraiser this week—hundreds of thousands took to Twitter on Thursday and overnight to criticize Clinton's contradictory record on a number of issues including marriage equality, race, healthcare, Iraq, and more.

The hashtag went viral—though Twitter, whose executive chairman Omid Kordestani recently held a fundraiser for Clinton, was later accused of censoring it. As of Friday morning, the hashtag had accumulated well over 350,000 mentions.

Sanders' supporters contributed to the conversation, the Huffington Post reported, "creating the hashtag #OnlyOneBernie to contrast Sanders' perceived consistency with Clinton's supposed two-faced nature."

Remember when Bill teamed w/ Bush Sr. to rebuild NOLA, and that included demolishing public housing + privatizing the schools? #WhichHillary — Naomi Klein (@NaomiAKlein) February 26, 2016

#WhichHillary the one who blamed homeowners for the 08 crisis or who blamed Wall Street. #WhichHillaryCensored pic.twitter.com/nRddrk6T7m — CDHill (@CDHill9) February 26, 2016

#WhichHillary the one who had the audacity 2 go 2 Flint & profess her sorrow, or the one who supported NAFTA that destroyed their economy SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





— GAPeach (@PoliticsPeach) February 25, 2016

#WhichHillary? Doesn't matter any more, the world has had enough of dishonest, corrupt politicians. There's a better choice. #OnlyOneBernie — Martin Emes (@martin_emes) February 25, 2016

Listen to any one minute of this video to see who Bernie has always been.https://t.co/ykBY9FZQIN

##onlyonebernie — Gerald Herb Wilmoth (@RockFlour) February 26, 2016

Seizing on another point of comparison, reporter writes at Bloomberg on Friday that "few issues show the contrast [between Sanders and Clinton] better than their relationship with Wal-Mart Stores Inc., America’s biggest private employer."

"Clinton used to sit on its board," Pettypiece points out. "Sanders has used the company as a model for inequality in America—comparing the vast wealth of the Walton Family, which owns the majority of Wal-Mart, to the low income of its employees, some of whom receive government benefits like food stamps and Medicaid."

Going into Super Tuesday next week, when 11 states hold primaries or caucuses, Sanders needs to hit certain targets in order to win the Democratic nomination.

As FiveThirtyEight's Nate Silver explained this week:

Our benchmarks suggest that Sanders ought to win Vermont, Minnesota, Colorado, Massachusetts, Oklahoma and Tennessee to be on track for the nomination. Sanders is going to rout Clinton in Vermont, of course; he’s also slightly ahead in Massachusetts polls, although not by as much as our targets say he “should” be. There hasn’t been enough recent polling in Colorado or Minnesota for us to make forecasts of the caucuses there, but we’d probably consider Sanders the favorite in those states also. Sanders trails in polls of Oklahoma (narrowly) and Tennessee (badly), however, when he probably needs to win those states too. Meanwhile, he’s losing states such as Georgia by a wider margin than our benchmarks suggest he can afford. The Democrats’ delegate allocation is quite proportional, so these margins matter; underperforming his targets on Super Tuesday would mean that Sanders would have to make up more ground later on with less time left on the clock.

Politico reported Thursday that "interviews with over a dozen state Democratic party chairs and local officials in Super Tuesday states suggest Sanders is within striking distance of Hillary Clinton in at least five of the 11 contests that will take place on March 1."