A few weeks ago, my colleague Ezra Klein spoke to a few hundred College Democrats. He told me a fascinating story about an unscientific, unrepresentative poll he took of the kids these days:

How many of you support Hillary Clinton? About a third of the hands went up.

How many of you support Bernie Sanders? About two-thirds of the hands went up.

How many of you think Sanders can win the general election? Only about a fifth of the Sanders supporters kept their hands up.

Anecdotes aren't the best data in the world, but for now it's the best we have on this particular question, and it suggests a key weakness for Sanders's impressive campaign: Many of his supporters like the idea of supporting him, but don't actually believe he can win. That raises the possibility that Sanders's support is soft and will melt away if Sanders looks like he might actually win. As Joe Trippi, who managed Howard Dean's 2004 campaign, told the Washington Post, "People get more pragmatic the closer they get to an actual vote."

It also raises the question of what Elizabeth Warren is up to these days. When Warren initially passed on the presidential race, the conventional wisdom was that even if Clinton wasn't as progressive as Warren, she was much more electable — a near-lock to win both the primary and the White House. Since then, though, Democrats have watched Hillary Clinton's lead in the Democratic primary slip, her lead in head-to-head polls against Republican candidates vanish, and questions over her email (and her campaign's inability to effectively respond to the email issue) mount.

The result is that the basic bargain of the Clinton campaign is breaking down: Democrats increasingly feel they need other options in case Clinton turns out to be much less electable than they thought. So far, that search has manifested in an odd yearning for a third Joe Biden presidential campaign.

But it's always been Warren — not Biden — who seemed like the person who could actually beat Clinton in a primary, who is a more charismatic campaigner than Clinton, who is better than Clinton at garnering positive media coverage, and whose record is more in touch with the populist mood of the electorate. And it's Warren — not Sanders — whom the left wing of the party wanted to recruit as its champion.

For Warren to get into the race at this point after shying away from running and then letting Sanders do the dirty work of demonstrating Clinton's vulnerability would be a little dishonorable. It's reminiscent of when Bobby Kennedy jumped into the 1968 primary only after Eugene McCarthy took the risk of challenging Lyndon Johnson in the New Hampshire primary. But Kennedy took the plunge for a good reason. He — like Warren, but unlike McCarthy or Sanders — actually stood a decent chance of beating the establishment favorite.

Warren has a far better shot than Sanders

On substance, the two New England liberals are very similarly positioned on the left wing of the Democratic Party's Senate caucus. But in political terms, Warren is a much stronger face for the left wing of the party.

For starters, Warren is, obviously, a woman and would allow progressively minded voters to support someone who's not Hillary Clinton without putting themselves on the wrong side of a potentially historic breakthrough for women in American politics.

Warren is also, as her recent defense of Black Lives Matter showed, very much in touch with the modern, ethnically diverse version of the Democratic Party. Sanders, by contrast, is a veteran of statewide races in the freakishly white state of Vermont. His campaign has made meaningful efforts to overcome some early missteps in its outreach to nonwhite voters, but a presidential election is a little late for a Democrat to still be studying up on this.

Which brings up another point: Warren is also a Democrat, rather than someone who's served in Congress for years while calling herself a socialist. This doesn't matter to everyone in America, but being a Democrat has historically been a major advantage in seeking the Democratic Party nomination, and calling yourself a socialist has generally not aided electability.

Last but by no means least, as a consequence of these other advantages, Warren stands a much better chance of attracting the institutional support of major labor unions.

Sanders's lack of such support is, thus far, the biggest shortcoming of his generally impressive campaign. Labor should be Sanders's natural base within the party, but risk-averse union leaders don't want to back a doomed cause. This must be a maddening Catch-22 for Sanders, who would be much less doomed with union support. But it's how politics is played in the real world. Warren's greater viability would garner her more labor support, which would make her that much more viable.

Warren has the appropriate theory of change for 2016

Beyond crass politics, though, Warren would inject something meaningful and important into the race. Sanders is in many ways a surprisingly effective legislator — someone who, despite his somewhat marginal ideological position on Capitol Hill, does an excellent job of crafting amendments that actually pass and finding co-sponsors for his various ideas.

The problem is that while presidents sometimes get to operate as legislators-in-chief the way Barack Obama did in 2009 and 2010, a Democratic successor to Obama is not going to be able to operate this way. The odds of a continued Republican congressional majority are overwhelming, and mean that the most important job the Democratic nominee will be running for is the job of regulator-in-chief.

That's a job to which Warren is perfectly suited.

She became a senator after running the Consumer Financial Protection Bureau — a major regulator. And as a senator she's made a name for herself not by writing laws but by second-guessing elements of executive branch conduct — whether it's trade negotiations, or SEC rulings, or assistant secretary appointments in the Treasury Department. These are not necessarily the most important subjects in the universe, but they are the most important subjects in the Democratic Party presidential primary given the specific circumstances of 2016.

Sanders and Clinton are likely to find themselves debating whether to propose a $12-an-hour minimum wage that Congress rejects or a $15-an-hour minimum wage that Congress rejects. Warren and Clinton could debate something non-hypothetical, like whether to seek a corporate death sentence for large banks that violate financial regulations. Sanders obviously can and will try to take on executive branch topics, but Warren is extraordinarily skilled at understanding where these levers of power really lie and is freakishly good at popularizing these obscure topics.

It's not too late

In retrospect, Warren should have gotten into the race months ago, back when everyone was writing articles about how she should get into the race. But even though the campaign feels like it's been going on since the beginning of time, it's not remotely too late for Warren to change her mind.

Nominating contests keep getting longer and longer, but there's no real need for this. Modern technology has drastically reduced the transaction costs involved in identifying potential supporters and communicating a message, and the relentless pace of modern publishing means the media would eagerly embrace a fresh storyline. The fact that Sanders is already in the race does present a serious problem for Warren, since the people currently supporting him are largely people she would ultimately be counting on. This is why acting sooner would have been better. Nevertheless, the fact remains that her political ceiling is higher than Sanders, and despite the vote-splitting problem she stands a better chance of defeating Clinton than he ever would.

Moreover, the case for Warren only improves if Biden enters the race, as polls show him splitting votes with Clinton.

If Warren genuinely thinks Clinton is a strong candidate, and that a Clinton administration would zealously represent her rules on the appropriate role of finance in the American economy, then that would of course be a good reason to stay out. But if — as seems to be the case — she is concerned that her populist vision may not hold sway in the White House even if Democrats win in 2016, then it's not too late for her to try to get the job for herself.