The Note: Biden gets last best shot in final debate before campaign goes national

The TAKE with Rick Klein

He is sliding from the center of the stage, and this is not the kind of moment former Vice President Joe Biden banked on having to have. But in the jumble that is the Democratic primary at the moment, he'll take it.

Tuesday night's debate in Charleston, South Carolina, will draw interest for former Mayor Michael Bloomberg's attempts to erase memories from last week, and for the pile on that the front-runner, Sen. Bernie Sanders, seems assured of facing.

Yet in his must-win state, amid Democratic Party panic about Sanders' momentum and whether anyone is positioned to challenge him, Biden faces a defining moment in the last debate before the campaign goes national.

Biden will take on Bloomberg and Sanders, of course, drawing on books both men are adding new chapters to as the campaign goes on.

But he will also have to take aim at Tom Steyer -- back on the debate stage after missing the cut last week, and perhaps a bigger threat to Biden at this moment. Plus he will need to emerge from a crowded lane that still also includes former Mayor Pete Buttigieg, Sen. Amy Klobuchar and Sen. Elizabeth Warren.

It's not just that Biden needs to see Bloomberg's prospects fade, despite his billions and his potential appeal as a backup option for many Democratic voters only now starting to tune in. It's not just that someone -- anyone -- needs to start beating Sanders, if the core argument of electability is going to stand on its own before Super Tuesday.

Biden needs a win in South Carolina to establish his ability to coalesce the Obama coalition, at a time when some Democrats are wondering if such a thing even exists -- or is necessarily relevant -- anymore.

The former vice president took what could be his best shot at Sanders, in a digital ad launched Monday in a state where well more than half of Democratic primary voters are expected to be African American: "When it comes to building on President Obama's legacy, Bernie Sanders just can't be trusted."

The RUNDOWN with MaryAlice Parks

It is one thing for Sanders' to defend old comments of his -- it's another entirely to explain statements he made this week.

The Sanders team spent Monday trying to spin comments he made during a CBS interview about Fidel Castro's literacy program in Cuba, by arguing that Obama also praised the small, communist country's strides in education.

But South Carolina Congressman Jim Clyburn called Sanders' comments an "unforced error," and many of Sanders' rivals pounced.

The comments did, after all, play right into the negative branding and lines of attack Sanders' opponents were already using against him.

Biden's campaign wrote in a statement Monday afternoon, "Make no mistake: Bernie Sanders' comments on Fidel Castro are a part of a larger pattern throughout his life to embrace autocratic leaders and governments across the globe."

The comments from Sanders will likely -- again -- reveal deep generational divides in the Democratic Party and reinforce the truism that Hispanic voters are not a monolithic block. But of course, they will also have an impact with a general audience too.

Not only could the comments further rattle Democrats already skeptical of the independent senator's political philosophy, but they could also worry those who might be inclined to like him but are anxious about his electability.

The TIP with Armando Garcia and Benjamin Siegel

After a rocky debate last week where he came under fire from every other candidate, Bloomberg and his campaign are aggressively setting their sights on front-runner Sanders.

"I'll just say that the debate tomorrow night and -- I think -- the campaign in general for folks in this race needs to be about one candidate, and that is Bernie Sanders," Dan Kanninen, Bloomberg's states director, told reporters on a Monday call.

Like Hillary Clinton in 2016, Bloomberg is attacking Sanders for alignment with the NRA earlier in his career, and a 2005 vote on a measure that would have protected gun manufacturers from lawsuits that held them liable in cases where their firearms were used in a crime.

The former mayor's released a digital ad questioning Sanders' record on gun control -- but has so far stopped short of airing negative attack ads on television, where he’s spent about $401 million promoting his candidacy across the country. Look for Bloomberg to sharpen those attacks against Sanders on the debate stage in Charleston -- the last time the candidates will appear together before the South Carolina primary and Super Tuesday.

ONE MORE THING

With a decisive victory in Nevada under his belt, Sen. Bernie Sanders has solidified his front-runner status in the Democratic primary, prompting his competitors to sharpen their attacks and question his electability in the lead-up to Tuesday night's debate in South Carolina. Unlike Nevada, there's no early voting in South Carolina, so this debate is timed to potentially sway voters.

THE PLAYLIST

ABC News' "Start Here" Podcast. Tuesday morning's episode features a full breakdown of the Harvey Weinstein verdict and what it means for the #MeToo movement going forward. Then, ABC News Senior White House correspondent Cecilia Vega checks in from India after President Donald Trump's massive rally in Ahmedabad. http://apple.co/2HPocUL

FiveThirtyEight Politics Podcast. Sen. Bernie Sanders won a decisive victory in the Nevada caucuses over the weekend. In this installment of the FiveThirtyEight Politics Podcast, Jon Ralston, editor of The Nevada Independent, joins Nate Silver and Galen Druke to break down the voting patterns that helped Sanders win and what they mean going forward. https://apple.co/23r5y7w

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