“Every bit of evidence about Elizabeth Warren is that she’ll go indie when she feels she needs to,” said Doug Schoen, a pollster and strategist who has advised Bill Clinton and Mike Bloomberg, referring to Warren’s carefully maintained identity as someone who doesn’t back down. If Clinton ran with her and won, “The day that Warren says, ‘I cannot support this trade deal’ that Clinton has decided to endorse, the administration is over.”

But the most compelling reason that Clinton can pick whom she pleases is the ineffably large, epically polarizing presence of Trump. Any wavering voters who might be lured his way will be making a decision about him — whether he’s a protest vote with too high a price, whether a real leader can bloom where a peevish child still stomps and preens — and not about the appeal of Clinton’s No. 2.

“The Trump card overwhelms it,” said Doug Sosnik, a Democratic strategist who worked in Bill Clinton’s White House, adding that if either candidate’s vice-presidential pick matters at all, it’s Trump’s. “He might be able to reassure people that there’s an adult on site.”

Not that he has many options, and that’s another facet of these veepstakes that makes them different from any other. In elections past, strivers in both parties deflected questions about the vice presidency with a coyness designed to make clear that, yes, they’d run a lawn mower over beloved relatives if those haplessly positioned kinfolk stood in the way of the assignment.

In this election, young Republican stars and seasoned party veterans alike have dispensed with any coyness to stress that they’d rather do yard work than stand beside the gaudy topiary that is Trump. Marco Rubio, Nikki Haley, John Kasich, Scott Walker and more said, “No, thanks,” before Trump could even say, “Please.”

And it’s not just that they reject positions Trump has taken, flinch at words he has spoken and worry that he’s more taint than gilt. They also fear how exposed they’d be.

NORMALLY, before a candidate and his or her aides choose a running mate, “They develop an operation to defend and support the vice-presidential nominee,” said Dan Senor, an adviser to Mitt Romney’s 2012 presidential campaign who helped do precisely that for Paul Ryan. “The minute that nominee is announced, there are 800 reporters breathing down your throat and the other side is going to war to shred the running mate’s reputation.”