Of all the arguments the Democratic establishment has thrown out against Bernie Sanders' candidacy, perhaps the most recurring one revolves around electability. “Sure, you agree with him,” they argue, “but he can't win.”

A just released CNN poll finds Sanders out-polling all of the GOP's major candidates, though pretty much tied with Jeb Bush. Here's how Sanders stacks up:

SANDERS: 48%

BUSH: 47%

SANDERS: 48%

WALKER: 42%

SANDERS: 59%

TRUMP: 38%

If you limit the poll sample to just registered voters, Bush defeats Sanders by a single point. Either way, this credible poll suggests that Sanders is not just some pie-in-the-sky general election candidate. His more uphill battle may be the primary. But even there, he has some strengths. Polling out last week shows he's the only candidate from either side who has a net favorability rating.

For the Republicans, too, the race is being turned upside down. Celebrity billionaire Donald Trump is now beating his rivals in national polls; the CNN poll has him at 18 percent to Jeb Bush's 15 percent. In state polling, Trump is the leader in New Hampshire in the Marist poll, at 21 percent, with Jeb Bush at only 14 percent. In Iowa, Trump is at 17 percent and Scott Walker is at 19 percent.

The race on both sides is slowly in the process of being turned on its head — a sign voters are frustrated with the status quo.