While candidates have yet to directly clash often, there are signs a moderate challenger might distinguish himself or herself by critiquing rival plans as too large, too costly or too risky.

In addition to Medicare For All, the Green New Deal is one area where there are signs of unease along these lines. Some candidates have suggested its goal of getting to net zero carbon emissions by 2030 is untenable.

“It’s a very ambitious and maybe excessively ambitious goal,” Hickenlooper said last week while praising its “urgency.”

Former Rep. John Delaney, who is running for president. went further, calling it “about as realistic as Trump saying that Mexico is going to pay for the wall.”