The vast Republican field has already had showdowns on two occasions that proved to be excellent spectacle. But, tonight marks the first time the U.S. viewing public has seen the Democrats take their podiums and attempt to spotlight their populist cred.

Wall Street will be rightly cast as the villain during the debate, it having absconded with the livelihoods and homes of millions though its reckless gambling. However, it remains to be seen how much of the candidates’ lines will be devoted to calling for a tax on Wall Street financial transactions as a way to hold financial institutions accountable for their actions that prefaced the 2008 financial collapse.

In place in the U.S. from 1914 through the end of 1965, (with a tiny fee still funding the Securities and Exchange Commission) financial transaction taxes are an “oldie-but-goodie” solution to the relatively new problem of high-frequency trading where computer algorithms outpace and upstage average investors. Exposed in Michael Lewis’ recent book, “Flash Boys: A Wall Street Revolt,” high frequency trading is the stuff of sci-fi A.I. — computer programs that sense minute market fluctuations and pounce on them. The microscopic profits made on each of those millisecond trades multiply exponentially over time.

Taxing Wall Street trades, then, should be as non-controversial as paying tax on Broadway tickets. Unfortunately, that’s not yet the case, and some media outlets still attempt to characterize the idea as fringe. Though a majority of the ensemble of Democratic candidates have supported taxing some portion of financial transactions like stock, bond, and derivative trades, it’s not clear whether mainstream media is ready to promote the idea from bit player status to star of the policy stage. But, tonight’s debate could flip the script and bring taxing Wall Street to the forefront of the financial reform discussion.

This is even truer since Hillary Clinton recently paid tribute to using a tax on trades as a solution to the problem of high-frequency trading when she proposed a “tax” on abuses of the market, such as excessive order cancellations. Though more akin to an automatic fine than an actual across-the-board tax on trades, last week’s pronouncement from her campaign showed positive movement toward reinstating a genuine Wall Street tax in our country. Bernie Sanders and Martin O’Malley have already endorsed the idea of renewing a robust tax on Wall Street trades, so it’s possible the media will seek to highlight this difference in the candidates’ stances.

It should also be said that in addition to reducing harmful high-speed trading, taxing Wall Street trades has the potential to net significant revenue. Detailed in a new report from Public Citizen’s Congress Watch division, “The Financial Transaction Tax: An Old Solution to a New Problem,” if the aforementioned historical U.S. tax on stock trades had not been repealed and sales volume had remained the same, the tax would have generated nearly $400 billion in today’s dollars for the half century spanning 1966 to 2014. Of that, $333 billion would have accrued since 2000. That would have meant an average of more than $22 billion a year in revenue since 2000.

That’s a lot of cash that our country has missed out on.

So, as the Democratic stars step out on the Vegas stage (with one potential addition waiting in the wings,) it would be great to hear a chorus of tough questions like: Do candidates support Main Street or Wall Street? And, who’s for slowing down high-speed trades while banking some serious coin for the government purse?

We have not yet reached the denouement; tonight’s debate is just an opening act as we approach the mid-point in the presidential campaign. We anticipate further revelations as the political drama continues to unfold.