...there's no real reason to think Clinton needs to court the left in the race going forward...In the May Washington Post-ABC News poll...Her numbers among "liberal" Democrats were...79 percent favorable with 48 percent of that bloc strongly favorable...

If Clinton doesn't have a problem on her left to solve, then adding Warren to the ticket only brings potential problems...a Clinton-Warren ticket might be the one thing that could convince lots of Republicans who are uncertain about Donald Trump to make a lesser-of-two-evils vote for the real estate mogul.Cillizza is exaggerating Clinton's strength on her left: if you also count "liberals" who don't identify as Democrats, instead of excluding them, her favorability drops from 79 to 59. But let's run with his number and unpack his argument as given.

Obviously, making a play for the 21% of leftists who dislike Clinton would not "only" bring potential problems - it would also bring her 21% of leftists. The actual argument here, left unstated, is that you could only win 21% of leftists at the cost of alienating

*more*people on the right. The reason Cillizza doesn't state this is that it's difficult-to-impossible to prove. What if the trade-off is just zero sum, and Clinton always earns a leftist for every rightist she alienates? What if she only alienates one rightist for every

*two*leftists she earns, so that moving left would not only improve her platform but also expand numbers? The Centrist argument here turns directly on a cost-benefit analysis that Cillizza doesn't even

*attempt*.

That's why it's not worth quibbling over whether Clinton's favorability among liberals is 79 or 59. It's not as if Cillizza's argument holds at 69 but mathematically breaks if Clinton drops to 68 or lower. There's no actual math at work here - just the ideological doctrine that you can always take the left for granted, and some meaningless numbers to lend the appearance of rigor.

Besides, if sensational numbers substitute for a rigorous argument, here's a simple one: 58%. That's how many "consistently liberal" respondents always vote, according to Pew. When we appreciate just how abysmal voter turnout in the US has always been, the notion of some shortage of leftists for Clinton to win over seems pretty absurd.