Hillary Clinton threw grassroots liberals a bone on Thursday by declaring Elizabeth Warren "qualified" to be her vice president. She didn't really say much more than that she respected Warren, and views her as "an incredible public servant, eminently qualified for any role." But given the intense fervor for a Clinton-Warren ticket among base Democrats, even that will probably be enough to get some hopes up.
It's remarkable how fast discussion of Clinton's running-mate selection process has been reduced to the question of if she'll pick Warren, but it's also understandable. Warren is probably the most popular and recognizable Democrat in the country apart from President Obama, Joe Biden, and Clinton herself. She's proven to be a very effective and eager anti-Trump campaigner, making headlines for her attacks on the Donald's business record, for sparring with him on Twitter, and most recently for a speech accusing the GOP nominee of exploiting the financial crisis for profit.
But the real reason Warren is dominating the conversation is simple: The rest of Clinton's options are very, very weak. And that means she's in a tougher spot than Trump is when it comes time to pick a running mate.
Hillary Clinton's vice presidential shortlist is really, really weak
While theoretically any senator or governor or even member of Congress is an option for vice president, in practice, presidential candidates almost always pick people who are already major national political figures. Usually that means picking a former presidential candidate: Biden, John Edwards, Jack Kemp, Al Gore, George H.W. Bush.
But even selections without a presidential run in their past usually have a national profile. Dick Cheney had been the defense secretary during the last major American war when he got picked. Paul Ryan's budget made him a household name and the voice of the anti-Obama opposition well before Romney picked him. Joe Lieberman was already prominent in 2000 due to his criticisms of Bill Clinton's adultery.
Going down the list, very few non-Warren candidates have anywhere near that profile, and the most frequently mentioned ones all have serious problems even leaving aside their relative anonymity.
Outside of Warren, Housing and Urban Development Secretary Julián Castro gets the most buzz, but he's laughably unqualified. He hasn't done much of note at the Department of Housing and Urban Development in the past two years, and he served as San Antonio mayor when that was a part-time job paying $3,000 a year plus $20 a council session; San Antonio uses a council manager system, where the mayor is basically a glorified city councilor.
Sen. Tim Kaine (D-VA) is in a swing state and speaks better Spanish than Castro from his time as a missionary in Honduras, but he also has a strong anti-abortion record that wouldn't be a great addition to the first woman-headed major-party ticket in American history.
Labor Secretary Tom Perez is popular with liberals, but Clinton probably wants a running mate who's won a more recent and notable election than the 2002 county council race in Montgomery County, Maryland.
Former Sen. Evan Bayh (D-IN) — perennially on Democrats' VP shortlist, including in 2008 — has ruled himself out by spending the past six years as a lobbyist. Not so attractive in a year when a democratic socialist decrying big money in politics ran a strong campaign against Clinton.
There just aren't that many famous Democrats to choose from
Sen. Sherrod Brown (D-OH) could help shore up Sanders supporters, but he's a key senator in a swing state whose replacement would be picked by a Republican governor. He's also not a national figure the way Paul Ryan, Joe Biden, John Edwards, or Dick Cheney was.
And the list of options who are national figures on that scale is very short. There's Bernie Sanders, of course. There's Warren. There's Biden (again). Al Franken was a reasonably well-known celebrity before taking office, but he has purposely not become nationally known as a politician the way Warren has. Martin O'Malley ran a whole presidential campaign but didn't earn the name recognition boost that Biden and Edwards did when they ran. New Jersey's Cory Booker is kind of well-known to media figures because Newark is close to New York City, but nationally he's still fairly obscure.
By contrast, the extensive Republican bench combined with Donald Trump's apparent total lack of concern about normally disqualifying candidate baggage means there is a huge number of nationally notable candidates he could pick: Newt Gingrich, Chris Christie, Sarah Palin, Ted Cruz, John Kasich, or even Marco Rubio.
With a more prudent nominee, the fact that Gingrich divorced his first wife while she was recovering from cancer, or that one of Christie's former top aides is now under indictment, might be considered a problem. With Trump, they're hardly limits.
That helps explain why the prospect of a Clinton-Warren ticket keeps coming up. It's not just that Warren is a potent attack dog against Trump; it's that she's basically the only available Democrat of sufficient stature to look like a plausible vice president.