On Thursday night, Emily Bell, who runs the Tow Center for Digital Journalism at Columbia, tweeted out this question:

I replied that it was roughly 10 percent. Others — like Politico's Ben White — said it was more like .1 percent.  The question — and the back and forth over it — got me to thinking what would happen on the very small chance that Clinton did decide not to run.  After all, she has only hinted at her interest publicly, and has yet to take the steps — leadership PAC, etc. — that would indicate clear interest. Virtually everything we know about Clinton's plans come from staff movements and quotes to reporters from "those in the know" who demand anonymity to share their knowledge.

I wrote about this possibility roughly a year ago and concluded that if Hillary stayed out, the result would be a crowded field with a nominal front-runner in Vice President Biden. And that Republicans' chances to win back the White House would immediately improve.

There's a different dynamic at work now — particularly if Clinton waits another few months to make clear exactly what she is going to do in 2016. We are rapidly approaching the point of no return for Clinton. That is, if she were to suddenly take herself out of the race in, say, two months' time, there would be a massive sense of doom within the party. The shock of the decision would reverberate for weeks — and maybe even months — making it hard for anyone looking to fill the void she left behind.

Now, that doom would eventually be followed by a wild scramble among the Bidens, Martin O'Malleys and, yes, even Elizabeth Warrens of the party for the donors, activists and staffers who had all been assumed to be part of the Clinton machine. But doing things in a hurry with what would widely be regarded as Democrats' "B" or even "C" team would be deeply problematic.

Simply put: For Clinton to pass on the race — and especially if she waits until summer to make her decision public — would be absolutely disastrous for her party's chances of holding onto the White House next November. She and her budding team have to know that, and it's hard for me to imagine that she would have let things go this far — there is, literally, an entire campaign and outside Clinton world already in place for her — if she had any serious or lingering doubts about whether she was going to make the race.

And, as has been true since day one, if she runs in 2016, she is an extremely heavy favorite to be the Democratic nominee.

Below we've ranked Clinton and the six other people who either will or could conceivably run for president against her.

7. Sen. Bernie Sanders (I-Vt.): Sanders appears serious about running, which is why he’s on this list. But while he’ll probably get real support from more liberal quarters of the party, his appeal is what you would call limited. Still, he’ll mix it up, and this week he questioned whether Clinton would be “bold” enough as president in an interview with The Washington Post. (Previous ranking: 6)

6. Former Virginia senator Jim Webb: As CNN's Dan Merica pointed out recently, Webb is running his campaign — he has formed an exploratory committee — largely via Twitter. Given that Webb has less than 5,000 followers, this may not be the most sound political strategy. (Previous ranking: 5)

5. California Gov. Jerry Brown: Bear with us for a second here. Brown is a popular governor of a notoriously difficult state to run, he has run for president before and he’s not exactly friendly with the Clintons. And, he's super-popular! He’s also 76 years old (even though he doesn’t look it or act it) and there’s little indication he’s seriously looking at running. But if he did…. (Previous ranking: N/A)

4. Vice President Biden: Biden assured us recently that he is serious about running for president in 2016 — probably because folks like us are increasingly dubious and because he hasn’t actually done much of the legwork to put a team in place. Even if he did run, we still have a hard time seeing him catch fire. He’s entertaining, yes, but “entertaining” ain’t “presidential.” (Previous ranking: 3)

3. Former Maryland governor Martin O’Malley: If there’s anybody who can conceivably beat Clinton by running to her left — and might actually run — it’s O’Malley. He’s got lots of liberal bona fides from his time as Maryland governor, and he checks lots of other boxes — even as he didn’t really leave office on a high note. But we would stress this is all on-paper, and O’Malley would still face very long odds. (Previous ranking: 4)

2. Massachusetts Sen. Elizabeth Warren: The drumbeat for Warren to reconsider her past refusals to consider running in 2016 has died down a bit in the last few weeks. That said, Warren backers commissioned a poll released Friday that showed significant unhappiness with Clinton among Democratic voters. Warren has the liberal profile and fundraising ability to be a serious problem to Clinton if she ever decided she wanted to be. (Previous ranking: 2)

1. Former secretary of state Hillary Clinton: See above. (Previous ranking: 1)