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So far, in the race to secure delegates for the party's nomination, Clinton has steamrolled ahead of the Vermont senator, but Sanders is hoping that the industrial Midwest and West Coast states come through for him in a big way. Tonight, the candidates return to Flint, Michigan, to make their case in a town they have both been before, which has been struck by tragedy and continues to seethe with frustration.
Here are five thing to watch for in tonight's debate:
THE CRISIS IN FLINT: Flint, the backdrop of tonight's debate, is undoubtedly going to be a topic front and center. The city's water crisis is one that Clinton and Sanders have both made a point of addressing on the campaign trail. Both candidates have visited the city, opened campaign offices there and have repeatedly placed blame on the state's Republican-led government for failing to prevent the high levels of led found in residents' tap water. Clinton has said it's something that would not have happened in an affluent community. And Sanders has even called for the resignation of Michigan Gov. Rick Snyder.
A TUSSLE OVER TRANSCRIPTS: Although he does not use her name, Bernie Sanders now regularly mentions Hilary Clinton's paid speeches to Wall Street firms while campaigning around the country. With biting sarcasm, Sanders often jokes that if Clinton's speeches were so good as to warrant hundreds of thousands of dollars a piece, then she must want to share them with the country. The lines draw big cheers from his crowds and the insinuation is far from subtle. By bringing up the issue it is clear that the progressive superstar does not fully trust that what Clinton is saying to voters is the same as what she is saying to bank executives. The Vermont senator is likely to level these attacks again tonight -- in front of a national audience -- and call for the former Secretary of State to finally release the transcripts of her speeches.
A TANGLE ON TRADE From blunt tweets to aggressive new ads, Bernie Sanders has seriously ramped up his rhetoric with regards to trade policy in recent days and worked hard to draw sharp comparisons between himself and Clinton on the issue. Knowing that he must breakthrough in key battleground states like Michigan, Sanders has tried to make the case that Clinton’s support of past free trade agreements like NAFTA have contributed directly to the collapse of manufacturing jobs in Midwestern cities. During this campaign season Clinton has broken with the Obama administration and her former Department of State to oppose the Trans Pacific Partnership, a flip that Sanders has said he remains skeptical about. Expect fireworks on this heated economic and foreign policy topic tonight.
THE DONALD TRUMP SHOW: No, Donald Trump will not be on the stage tonight -- but expect his presence to once again be felt as both Clinton and Sanders are likely to continue to bash the Republican frontrunner. In recent weeks, Clinton has shifted much of her focus to the GOP field (namely, Trump), and her biggest applause line now comes when she takes a knock at his campaign slogan. Sanders, too, routinely takes shots at the Donald. Their shared message? Either one of us, is better than him.
AN AIR OF INEVITABILITY: One of the things Clinton's campaign aides dislike more than anything is the oft-held notion that the Democratic presidential frontrunner is the party's inevitable nominee. But tonight, Clinton is coming into this debate more confident than ever and could end up projecting this persona herself. Her campaign believes she will rack up enough delegates by mid-March for Sanders to be too far behind to ever catch up. She's now walking a fine line between appearing like a general election candidate, while still appealing to progressives and firing up the base.