Is Warren really Hillary's nightmare? Hardly.

Let's talk about Elizabeth Warren and her political ambitions. Because, you know, somebody has to.

The Harvard professor turned bank-busting senator is now all the rage among the 2016 handicappers. (Rand Paul was last month. Please keep up.) The populist groundswell for Warren actually started last fall, when The New Republic put her on its cover over the headline "Hillary's Nightmare." And now that she's everywhere plugging her new memoir, Warren can't seem to get 10 feet without some reporter asking her if she's considering a primary campaign against a certain grandmother-to-be.

"I'm not running for president," Warren says to this. Which would be more convincing if she hadn't tantalizingly titled her book A Fighting Chance, which is exactly the kind of meaningless, vanilla cliché that only presidential candidates use for book titles.

But here's the thing: Warren is not, in fact, Hillary Clinton's nightmare. (Anyone who was alive in the '90s knows that Hillary has already lived through her worst nightmare, anyway, but let's leave the past in the past.) In reality, if you're Clinton, a challenge from Warren could be the next best thing to no challenge at all.

As I've written here before, I don't buy the notion that Clinton can clear the Democratic field. Franklin Roosevelt himself could rise from the grave and immediately form an exploratory committee, and even he wouldn't be able to scare off all comers in the modern environment, where money and manpower aren't nearly the obstacles they used to be.

No, should Clinton ultimately decide to run, someone will emerge to channel the energy of the antiestablishment opposition, to portray her as too compromising and too corporate. And she could do a lot, lot worse than to have that someone be Elizabeth Warren.

I understand the case for Warren. The reclaim-the-soul-of-the-party crowd will tell you that their moment has finally arrived. Inequality, a word you barely heard in politics even five years ago, is now a staple of cable TV. New York's new mayor, Bill de Blasio, is leading a populist renaissance even while finding time to emancipate the carriage horses in Central Park (over the objections of a very exercised Liam Neeson, which is weird only if you don't live in New York). Americans are fed up with falling wages for workers and soaring bonuses for CEOs. Warren, they say, isn't just some fringe figure; she embodies the moment.

Well, OK. But let me offer a slightly more skeptical view.

Democratic primary campaigns pretty much always come down to a front-runner versus an upstart, and those upstarts come in two varieties. The first presents himself (or herself) as a credible alternative to the status quo candidate – more desirable to grassroots activists on account of celebrity or charisma or some galvanizing issue, but also moderate and electable enough to reassure the party establishment. This was Gary Hart running against Walter Mondale in 1984, or Bill Bradley taking on Al Gore in 2000.

We already know that Clinton is vulnerable to this kind of challenge – because it's exactly what derailed her in 2008. Barack Obama used his antiwar status and personal story to differentiate himself from Clinton on the left, while presenting himself to the rest of the electorate as younger, less divisive and less inflexible. (It was Obama, remember, who during the primary campaign publicly praised Ronald Reagan, and opposed an individual mandate for health care because he said he wasn't comfortable with the government telling you what to do.)

The second prototype of challenger holds himself out more as a vehicle for ideological purity, urging a return to the populist convictions for which, it is always said, an anxious public is clamoring. This is Jerry Brown in 1992 or Howard Dean in 2004. These kinds of candidates often have a serious impact on the debate, but invariably they fall apart even before the delegates start rolling in, because anger as a primary emotion has a low ceiling in American politics, and because, at the end of the day, the vast majority of primary voters care more about winning than they do about sticking it to the establishment.

Which brand of challenger do we really think Warren would be? We're talking about a Cambridge academic who doesn't want to just preserve entitlement programs in the face of retiring boomers, but expand them. Next to her, Dean looks like Barry Goldwater.

Warren's backers are probably right that there's a wide lane in Democratic politics for running against corporate excess, and if Clinton doesn't run, an incursion like that might really take off. But as John Edwards found out in 2008, it's not an easy thing to portray Hillary as a stooge for Wall Street, no matter how much of its cash she vacuums up. For most Democrats, her last name is still synonymous with the prosperity of the '90s, which is one reason why – even after she publicly rushed to the defense of Washington lobbyists – working-class white voters overwhelmingly supported her over Obama.

 And if you're assuming that Warren, given her singular status as a populist crusader, could rival Clinton's support among independents who vote in the primaries, then consider this: After Scott Brown, whom Warren unseated in 2012, announced he would challenge Jeanne Shaheen across the border in New Hampshire, the Politico reporter James Hohmann asked Shaheen if she would want her fellow senator to come north and campaign with her.

"New Hampshire is different than Massachusetts," was Shaheen's unenthusiastic response. "We have, well, we're the 'Live Free or Die' state. We're independent."

If Warren isn't necessarily a plus against a guy she's already beaten in a state a half-hour from Boston, which also happens to hold a kind of important presidential primary, then how do we think South Carolina's going to turn out?

It's not just that Warren would be something less than a nightmare for Clinton; in fact, her candidacy would probably strengthen Clinton's general election prospects more than any other potential challenge. Clinton's vulnerabilities are well-known: She can be framed as too doctrinaire, too lecturing, too loose with facts (like the time she said she and Sinbad had almost been shot down in a plane, which turned out to be almost true, in the sense that she and Sinbad had been in a plane, and guns do exist.) Her supporters worry that sexism could be her most formidable hurdle.

Imagine, though, how doctrinaire and lecturing Clinton would seem, by comparison, after sharing a debate stage with Warren for six months. Imagine how much of an exaggerator Clinton would appear to be after Senator Stands With a Fist got through explaining, for the 400th time, why she claimed to be Native American in a faculty directory. And surely it would be hard to see Clinton's campaign as some kind of feminist statement after she'd buried a fellow woman under a barrage of attack ads.

If Clinton passes on 2016, I'd expect Warren to reconsider her demurrals, and maybe she should. But Warren's got to be too smart to swallow the hype about taking on Hillary. A fighting chance is about all she'd have.