Warren is perhaps one of two senators most associated with a form of liberal populism that is clearly ascendant in the Democratic Party. While Senator Bernie Sanders, I, rose to prominence in the 2016 presidential race with a message decrying a "rigged" system, Warren has been using such language for years. In the first TV ad of her 2012 Senate campaign, in November 2011, she said, "Washington is still rigged for the big guys, and that's got to change."
And her efforts to crack down on corporate malfeasance date to before that campaign. As a Harvard University professor, she laid the groundwork for what became the Consumer Financial Protection Bureau.
Put plainly: If Democratic voters are looking for the kind of candidacy Sanders was selling in 2016, Warren has about as good a claim on it as Sanders does - if not better. And as Sanders and President Donald Trump showed in the 2016 primaries, populism has broad appeal, when packaged correctly. That's why I had her at No. 1; there is so much upside.
But it's not clear there is the same populist desire on the Democratic side as the GOP side. Sanders performed well even in defeat, yes, but part of that undoubtedly owed to Hillary Clinton's weakness as the Democratic front-runner.
And an October 2016 University of Maryland poll actually showed significantly fewer Democratic voters strongly agreed that the system was "rigged" against them (16 per cent) than Republicans (35 per cent) and independents (43 per cent). That may have been due to Trump's focus on that message, but it's worth entertaining the idea that Sanders' success wasn't all about a liberal yearning for a populist uprising.
There is also the possibility that Warren will be fighting for the same voters as Sanders, who is considered a likely 2020 candidate and would undoubtedly be one of a handful of front-runners - if not the front-runner. The race will undoubtedly be very crowded, scrambling the idea of any one candidate monopolising a "lane." But the likely battle between Warren and Sanders for the 2016 Sanders voters is a major subplot involving a tranche of voters who could prove decisive.
Black voters:
While the size of the populist tranche is up for debate, there is no disputing the huge influence of black voters on the Democratic nominating contest. And that's an area where Warren, like Sanders, could suffer.
As the Republican Party has become whiter and more male in recent years, the Democratic Party has trended in the opposite direction.
In 2016, about one-quarter of all Democratic primary voters were black, and their strong preference for Clinton was a big reason she secured the nomination. Fully 78 per cent of black voters supported her in states where we had exit polls available, and she won virtually every state with a large black population. That's an especially big deal given that Southern states feature heavily on Super Tuesday.
But while Warren has tried to make inroads with black voters - including being one of the first white politicians to endorse the Black Lives Matter movement - there's little evidence of progress. Few black leaders came to her defence when she recently released a DNA test showing a distant Native American relative. She also faces the prospect of two black Democratic senators - California's Kamala Harris and New Jersey's Cory Booker - running against her.
From the Washington Post's Annie Linskey, a former Boston Globe reporter who has covered Warren for years:
"Warren has been travelling around the country to speak in front of black audiences, added black staffers in key roles, and cultivating key black leaders. But there remains an awkwardness she hasn't quite addressed, according to strategists who focus on the demographic.
"The reasons include her message of economic populism that can clang in the community, her ties to Boston and her DNA test, which dredged up ugly reminders about defining ethnicity."
"She would have done much better not to address Trump's racism," said Aimee Allison, the executive director of She the People, a group that supports non-white female candidates.
Allison's group released a straw poll of black female activists and strategists earlier in December that illustrated how much work Warren has ahead of her among those influential leaders. Just 22 per cent picked Warren as one of their top three candidates.
Age:
One of the biggest questions for Democrats in 2020 - as it has been since the 2018 election - is whether there will be a call for generational change. Like their congressional leadership, the Democrats' crop of 2020 front-runners skews older. And while Warren isn't a septuagenarian like Sanders, Joe Biden, Michael Bloomberg or Hillary Clinton, she will be come June 2019. If the party demands youth as a counterbalance to the oldest newly elected president in history, Warren isn't it.
But there are a couple mitigating factors. One is that Warren has been on the political scene for less than a decade - which will help her fight back against the idea that she's part of an entrenched political class that requires uprooting. Second is that she doesn't really project "senior citizen." Most voters will likely be surprised to learn she's only eight years younger than Sanders.
The DNA test - and divisiveness:
To the extent primary voters are strategic and just want someone who can beat Trump, Warren might not be it. While she quickly became a liberal star when she joined the Senate, there is a real argument to be made that a Harvard professor from Massachusetts is not what the party needs in the 2020 general election.
It's worth noting here that Warren is originally from Oklahoma and was a registered Republican until her 40s.
That's in large part because she's such a divisive figure - the kind of bogeywoman Trump thrives on attacking. Trump seems to relish feuding with Warren just like he relished feuding with Clinton. And a divided electorate is how Trump won in the first place, despite only 4 in 10 Americans liking him.
Warren also clearly has some liabilities, starting first and foremost with that DNA test. It was clearly an attempt to put to rest an old controversy that had dogged her dating back to her 2012 campaign, when her past claim to Native American heritage was cast by Republicans as an attempt to obtain unwarranted Affirmative Action.
That Warren finally decided to get a DNA test and release it was an unmistakable sign of her 2020 intentions, but it also went poorly. The Cherokee Nation's secretary of state called it "inappropriate and wrong" and said it made "a mockery out of DNA tests and its legitimate uses while also dishonouring legitimate tribal governments and their citizens, whose ancestors are well documented and whose heritage is proven. Senator Warren is undermining tribal interests with her continued claims of tribal heritage."
A Quinnipiac University poll earlier this month showed independents had a negative impression of Warren, with 41 per cent viewing her unfavourably and 24 per cent viewing her favourably.
None of this is to say she couldn't win - and there is an argument that you fight a fire-breather with a fire-breather. But Democrats saw in 2016 what can happen when 6 in 10 Americans dislike their nominee, and that's a distinct possibility with Warren in 2020.