Tonight the two Democratic candidates — Hillary Clinton and Bernie Sanders — meet in Miami for a debate.

Before Tuesday night, the debate was looking like an unimportant afterthought to a race that could have been all wrapped up. But not anymore, after Sanders' stunningly unexpected win in Michigan last night.

Here are three things to watch:

1. Delegates or momentum?

Hillary Clinton's campaign says all that matters is delegates and by that measure she succeeded Tuesday night — increasing her delegate lead over Bernie Sanders. But her loss to Sanders exposed troubling weaknesses for Clinton which she needs to address tonight.

How will she try to woo independents (which she lost) and white working class voters (which she almost lost)?

2. Sanders' new lease on life

Just when pundits were getting ready to call him irrelevant, Sanders is now set up nicely for Ohio — another big Rust Belt state that votes next Tuesday.

Tonight in Miami, will he raise the electability question: If Clinton lost Michigan to a Democratic populist in March, why wouldn't she lose Michigan to a Republican populist (Donald Trump) in November?

3. The enthusiasm gap

Republicans keep on posting high turnout levels. Democratic turnout is below 2008 levels.

In addition, the news media are inclined to cover a rambling 45-minute infomercial by Trump — billed as a presidential style news conference — instead of speeches by the other candidates.

If Trump is the nominee and continues to drive ratings, the Democrats might be gasping for airtime this fall.

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