While Hillary Clinton was in the process of getting beaten by Bernie Sanders in Michigan Tuesday night, the MSNBC crew began speculating about a possible running mate for Hillary, and inevitable, someone brought up populist liberal darling Senator Elizabeth Warren (D-MA). That someone was Lawrence O’Donnell, but really, it could have been anyone, since there seem to only be bad ideas floated for Hillary’s ticket. Here’s what O’Donnell had to say:

I think the best person she can possibly choose is Elizabeth Warren, who remains the most exciting non-presidential-candidate in that party. When you see Elizabeth Warren take a stage with a Democratic audience, there’s nothing quite like it, and Elizabeth Warren has all of Bernie Sanders’ credentials. You have a complete transfer of Bernie Sanders’ allegiance to Elizabeth Warren on minute one, if that’s the way this turns out.

One of the many problems with Warren as a VP pick is illustrated by the fact that O’Donnell was arguing against the panel’s consensus that Hillary ought to pick Sen. Sherrod Brown (D-OH), who accused President Obama of being sexist for calling Warren “Elizabeth,” creating instant bad blood with the immense Obama wing of the party. As bad a pick as Warren is, all Brown delivers is that crucial Voters Who Get Excited When They’ve Never Freaking Heard of You demographic, while alienating Obama supporters.

O’Donnell also isn’t alone in calling for a Clinton/Warren ticket. On the last episode of Real Time, Bill Maher floated the idea as well, and Matt Lewis gave the panel a case of the vapors when he shot the pick down with aplomb:

Elizabeth Warren is actually, like, a couple months younger than Hillary, which is old. Very Old. (audience boos) I think she needs to balance the ticket. Julian Castro.

Warren is, in fact, almost two years younger than Hillary, who is younger than Saint Ronald Reagan was when he assumed office. However, Lewis did have a point in that Hillary’s running mate could potentially be the Democratic nominee for president in 2024, after her second term ends. With that consideration, a younger nominee makes a certain amount of sense.

The main problem with Warren as a VP is that she’s just not qualified to be president. She excels within her lane of reigning in banks and protecting consumers, but has little interest in, let alone aptitude for, foreign policy. Like Bernie Sanders, Elizabeth Warren would be a liability in an election in which the Republican nominee will work the terror pole like Miley Cyrus. I doubt Warren herself would express any interest in holding nuclear codes.

Not for nothing, there’s also the fact that Warren used to play for the other side. During an election in which the 1990s are being re-litigated, Warren wasn’t just a bad liberal then:

I was an independent. I was with the GOP for a while because I really thought that it was a party that was principled in its conservative approach to economics and to markets. And I feel like the GOP party just left that. They moved to a party that said, “No, it’s not about a level playing field. It’s now about a field that’s gotten tilted.” And they really stood up for the big financial institutions when the big financial institutions are just hammering middle class American families. I just feel like that’s a party that moved way, way away.

Such is Warren’s tunnel vision on economics that she was a Republican until 1996, two years into Newt Gingrich‘s speakership, and well into the golden age of Republican racism. The Jesse Helms “white hands” ad was okay, but their approach to markets was the last straw?

But I also have to agree with Bill Maher that there is far too much “old thinking” when it comes to choosing a VP, that the right pick will deliver a state, or balance out a perceived weakness, or bring along a particular voting block. Julian Castro, for example, is supposed to deliver young voters and Hispanic voters, but he’s got absolutely no resumé at this point, and would lose Hillary the all-important People Who Care if the Vice President Can Be President vote. The HUD secretary is who you put in an undisclosed La Quinta during the State of the Union, not on your presidential ticket.

No, the first consideration for any VP pick needs to be that it does’t hurt you, the way Sarah Palin hurt McCain. Then, if you can pick up some votes along the way, fine. Yes, Hillary is going to need the Bernie/Warren wing, but she’ll have to get them through endorsements, and perhaps by floating them for prominent positions in her administration. As for Hispanic voters, if they don’t turn out to stop lunatics like Ted Cruz and/or Donald Trump, then a spot on the ticket won’t help.

There is, however, one pick who checks off every box for Hillary Clinton, who matches her strengths without hurting the ticket in other ways, who gives her the opportunity to groom a successor, who delivers broad support both from the Democratic base and independents, and who won’t fold in a debate with the Republican VP candidate. Hillary Clinton should pick Joe Biden as her running mate, for a single term as vice president.

Biden has the chops, the name ID, and a reservoir of goodwill among Democrats, Obama coalition voters, and the working-class white voters that Donald Trump is attracting, plus the toughness to stand shoulder-to-shoulder with Hillary, and toe-to-toe with the Republicans. Unlike a lesser-known pick, there will be no surprises with Joe Biden, and his free-wheeling style is a perfect counter-punch to the Trump phenomenon that would also afford Hillary the luxury of remaining a few feet above the fray.

A third Biden term would also give the deep Democratic bench time to come into focus, and perhaps shore up thin credentials like Castro’s.

Hillary Clinton’s greatest asset in this general election will be her toughness, and that’s an asset she can’t afford to have diluted by a weak running mate. Joe Biden is the rare pick that can match her toughness without overshadowing her, and whose unique resumé makes him something of a Rosetta Stone for huge groups of voters.

Then, after he’s served his four years, and helped shepherd the confirmation of Chief Justice Barack Obama, Biden can make way for the next VP pick when Hillary runs for her second term.

This is an opinion piece. The views expressed in this article are those of just the author.