It is not news that I think Elizabeth Warren is the best person for the Democrats to nominate for president in 2020: the best bet to unite the party, to lead it to victory in the general election, and to be a successful president once in office. I made my case back in October of last year, and I've seen no reason to change my mind.

That doesn't mean I think Warren has done everything right since then. I think she's running a real risk in positioning herself so far to the left on such a wide range of issues (particularly immigration). And she obviously handled the question of her claims to Cherokee ancestry very poorly. But every candidate makes mistakes and errors in judgment. The question is not whether she's doing everything perfectly but whether she is demonstrating the overall qualities that make her a strong nominee, and a potential president. She most assuredly has done that.

Now, events have transpired to put her in a position to seize true front-runner status. Joe Biden's aura of electability is likely to be dented, however unfairly, by the impeachment inquiry, simply because he'll be forced to defend the propriety of his conduct with respect to Ukraine. And Bernie Sanders, Warren's main competitor to the left, has been temporarily taken out of action for heart surgery. If she plays the next few weeks right, she could consolidate support, and be in a position to use the bulk of the primary campaign to sharpen her argument for the general election.

Here are the key obstacles to her achieving that goal, and my own sense of what it will take to overcome them:

1. Black voters

I've noted before that a key challenge for Warren is her tepid support among African-American voters. I suspect her weakness with this key demographic has several components to it: loyalty to Obama's vice president; a general risk-aversion and distrust of promises of radical change; a cultural distance shared with white working-class voters from a candidate who appeals most strongly to the most-educated segment of the electorate; and a simple lack of establishment support, including endorsements from major black elected officials.

That may be starting to change, slowly. I suspect Warren is beginning to pick up support draining away from Kamala Harris's flagging campaign more than she is peeling voters away from Biden, but it ultimately doesn't matter, so long as she is perceived as a viable contender for black votes. If she is, then a strong showing in Iowa and New Hampshire could lead to a bandwagon effect, rather than circling the wagons around her strongest opponent.

What does she need to do to achieve that? Primarily, keep showing up, and connecting her core argument to the specific needs of African-American voters. Warren's economic message is well-aligned with where black voters mostly situate themselves. Precisely because of that, the challenge is more about building relationships and instilling confidence than it is about positioning. If anything, Warren would probably benefit more with black voters by proving she can win over moderate, downscale white voters than she would by focusing on racial issues specifically.

There is one specific area that may be touchy, however.

2. Obama loyalists

Warren's greatest strength is that she is genuinely her own person, something she demonstrated during the early years of the Obama administration when she fought furiously with his economic advisors to be tougher on the banks and give more attention to the ways that stabilizing the financial system was insufficient to restore economic health. It was a vital practical issue as much as an issue of justice, and she wasn't daunted in the slightest by going to battle with her own party over it. Because of this history, she is uniquely positioned to cut the legs out from Trump's argument that he is a necessary disruptor of the system, and to seize the mantle of change rather than restoration.

But of course, an argument for "deep structural change" implicitly criticizes the popular former president, whether for failing to achieve that change or for failing to try. That's a potential problem for her as she seeks to consolidate support from moderate Democrats in general — and from black voters in particular. And Biden will do everything he can to make it as big a problem with as many voters (and party leaders) as he can.

Warren has been careful not to attack Biden for this very reason — indeed, she's been notable for rarely attacking anybody in her party. But when the argument is brought to her, she's going to have to figure out how to turn it to her advantage — by shifting the subject from the past to the future. The question isn't whether Obama made the right choices in 2009 or 2010 or 2014 or whenever. What would he do now, knowing what he does now, about what worked and what didn't, and what the consequences were?

Posing the question that way even allows Warren to reframe points of possible continuity with Trump's own policies (for example, unwinding our deep economic integration with China) as changes Obama himself was going through (the pivot to Asia was, itself, a strategy for responding to the Chinese challenge, albeit a different one). And it puts Biden in the position of defending his past decisions rather than charting a way forward.

3. The left

Warren made a point during the last debate of saying that she was "with Bernie" on Medicare-for-All, and in general she has been lumped in with Sanders as somewhat interchangeable left-wing progressive candidates. That's not an entirely fair characterization; Warren has consistently described herself as a believer in free enterprise and fair competition rather than as a democratic socialist. But she and Sanders do genuinely agree on many policy matters, and her credibility with the left wing of the party will be essential to her ability to consolidate their vote if Sanders weakens.

There's a tightrope Warren has to walk, though. Warren cannot consolidate overall support if she is viewed as a purely factional candidate. And she can't embrace the left-liberal position on every issue without coming off as extreme in a general election. But she also can't count on the loyalty of Sanders' supporters unless they believe she is committed to their cause.

Warren has done an excellent job to date of walking that tightrope, and has built an impressively loyal following of her own while also building bridges within the party. But that task is about to get more difficult as Warren positions herself as the right candidate to win the general election. She can't walk back her commitments. What she can do is clarify her priorities — and tell a clear, compelling story about why those are her priorities, one that could convince moderates and left-wing voters alike that they can trust her.

She has that story to tell. It's a story about systemic corruption, about crony capitalism and the capture of the government by corporate interests and the ultra-rich. It's exactly what Trump claimed to be running against and exactly what he has exacerbated tenfold. It's what got her into politics in the first place. If she sticks to it, it's hard for me to imagine the left holding out on her for lack of total purity, or moderates being alienated from her as someone too extreme or elite and out of touch.

Warren has gotten this far by embracing her identity. The good news for her is, if she digs down to the core of that, and doesn't let herself get distracted, she'll find all she needs to go the distance.

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