First we saw the incredible shrinking Scott Walker. Will the next act in this primary season's three-ring circus be the incredible shrinking Hillary Clinton?

The latest Bloomberg poll contains three pieces of bad news for Hillary. First, she leads by only 8 points nationally. Second, Joe Biden has narrowly overtaken Bernie Sanders as the runner-up. Finally, she's taking just 33 percent of the Democratic vote.

No, the sample size isn't overwhelming, though it's consistent with other national polls that were once more favorable to Clinton. No, it's not as important as what's going on in the early primary states, though it should be noted that Clinton is losing one, perhaps two, of those to Sanders.

But it's a possible sign the Democratic front-runner will fall back with the rest of the pack, like her 2008 race against Barack Obama and John Edwards, if the vice president gets in.

The hope, of course, for Team Hillary is that Biden's numbers will fall once he gets in and ceases being Uncle Joe the friendly theoretical candidate. But they could just as easily rise, like Trump's did after he got in. There's also the possibility that Biden would split the anti-Clinton vote, even if he is less of an ideological fit for it than Sanders. Even with a split, however, this poll has Biden within 10 points and the anti-Clinton vote exceeding Hillary's by 51 percent to 33 percent.

Maybe this is why the Clinton team is so peeved about reports they're worrying about Biden? I know, that's something only a political editor could believe.