Sen. Elizabeth Warren (D-Mass.) and former Secretary of State Hillary Clinton. (J. Scott Applewhite/AP; Jim Watson/AFP/Getty Images)

Hillary Rodham Clinton, after much debate within her inner circle, appears to have put off formally entering the 2016 presidential race until spring 2015.

Although there are plenty of reasons that favor waiting — legal ones in terms of how she incorporates (or doesn’t) the various outside groups that have blossomed in support of her in the past few years, and political ones about looking less, well, political, for as long as possible — there’s also a big reason she should at least consider announcing sooner rather than later.

And that reason is Elizabeth Warren. Or, at least, the energy and passion among liberals that is, at the moment, channeled through the Massachusetts senator. An attempt to draft her was launched formally last week, and her stern opposition to the $1.1 trillion spending bill because of a provision that would ease derivative trading by corporations drew scads of national coverage.

That’s not to say that Warren is running or even thinking about it at the moment. But let’s say the next three months play out like the past three months. The dominant narrative remains that Clinton is the heavy favorite to be the Democratic nominee. But that storyline is accompanied by another one — which is that the heart of the Democratic Party really wants Warren. And, as that storyline continues, more and more people hear about it and a movement develops, fueled by the anti-Wall Street populism that Warren embodies.

If Clinton waits until April, let’s say, to announce, it’s uniquely possible that the populist/“draft Warren” movement in the party grows strong enough that it forces the senator to reconsider her past denials of interest in the race. And if Warren runs, it’s a totally different race for Clinton. (To be clear, Clinton would be a favorite over Warren. But not a huge one.)

So, why not get in earlier, before the Warren movement gets any more energy or excitement behind it? Plus, the sooner Clinton gets in, the sooner she can start raising the money and building the campaign infrastructure that should be her biggest advantage in the race. And what if she used her formal campaign announcement to deliver a message on income inequality — sending a signal about how central that idea would be to her candidacy in 2016?

In short: Make it as hard as humanly possible for Warren to reconsider, and for the movement trying to get her to reconsider to gain steam. Be the prime mover. Act and make Warren, and everyone else, react.

Below are our rankings of the six people either running, talking about running or being talked about as potential candidates for the Democratic nomination. There aren’t 10 people listed because there aren’t 10 people seriously considering the race. The candidate ranked No. 1 — let’s not pretend here, it’s Clinton — is considered the most likely nominee.

6. Sen. Bernie Sanders (I-Vt.): Sanders is not a Democrat — he’s a socialist — and he’s not going to win the Democratic nomination for president. Yet he appears on this list. Why? Because there’s a decent chance he will run. And that’s more than we can say for a lot of folks. For now, Sanders is the most likely outlet for liberals who think Clinton is too closely allied with Wall Street. But the idea that a guy who calls himself a “socialist” is going to gain real traction in this race is hard to believe.

5. Former senator Jim Webb (Va.): The one-term senator is the first real entrant in the 2016 presidential race. And there won’t be a more surprising candidate. That’s because Webb retired from the Senate after just six years, having never seemed to enjoy the political process very much — especially the campaigning. The fact that this is the guy some are holding up as a more liberal alternative to Clinton doesn’t really make sense. But he is a former senator and Navy secretary, so he’s got a somewhat national profile.

4. Maryland Gov. Martin O’Malley: A few years ago, O’Malley would have been seen as Clinton’s biggest obstacle. He’s a capable politician and a two-term governor, and he has national experience as chairman of the Democratic Governors Association. But O’Malley’s two terms as governor ended on a low note. His approval rating dropped to 41 percent (in a blue state), and his lieutenant governor lost in the most shocking upset of the 2014 election. O’Malley seems one of the most likely big-name politicians to run, but he’s hardly looking strong these days.

3. Vice President Biden: He’s a two-term vice president and a longtime senator, and he wants to run for president. Yet almost nobody thinks Biden can give Clinton a run for her money. The reason? He’s a little too “Uncle Joe” and not really “President Biden.” We keep going back to it, but we think it’s illustrative: A Quinnipiac University poll last year showed that 65 percent of Americans didn’t think Biden would make a good president. And only a bare majority of Democrats (51 percent) said he would. Biden needs to show a more presidential side before he has a shot. He also needs Clinton to not run.

2. Warren: Warren is the beating heart of the Democratic base. She is also the only person on the list other than Clinton with a track record of raising lots (and lots) of money. (Warren raised $42 million in her 2012 victory over then-Sen. Scott Brown.) Combine those two factors and you see why the possibility — albeit slim — of a Warren presidential bid intrigues so many. She still is giving no indication that she wants to run. But, if she does run, Warren would be a bad matchup for Clinton and could give the former secretary of state real problems.

1. Clinton: The Warren buzz has to make some longtime Hillary allies a little skittish, reminding them of another liberal firebrand senator six years ago. Given that experience, however, Clinton (and her people) should be more ready in the unlikely event that Warren does reverse course and run. During the past year, Clinton has been talking much more about income inequality — a clear rhetorical bow in Warren’s direction and a subtle attempt to co-opt the energy forming behind the senator. Assuming that Warren stays out, Clinton starts the primary further ahead than any non-incumbent in modern history.

Aaron Blake contributed to this report.