Why the Joe Biden trial balloon is being floated.

Hillary Clinton

The idea of Joe Biden getting in the race is to see just how vulnerable Hillary Clinton might be. If Biden throws his hat in the ring and Clinton’s numbers take a hit as a result, then she’s not as strong a candidate as the party needs.

On the other hand, liked or not, Hillary Clinton still leads Republican rivals in the national polls. But once the general election season rolls around, if Clinton’s negatives are still high, that gives the GOP a strong card to play against her.

It may be a very good idea to let Biden get in. He doesn’t have the negatives Clinton does, and the only cards the GOP could play against him are not effective. He just may be a stronger candidate than Clinton. At this point however, he’ll have to make up a lot of ground.

There’s still a long way to go, but Clinton has a real problem that should not be dismissed.

The bad news for Hillary Clinton in the new NBC News/Wall Street Journal poll: More Americans view her negatively than they did a month ago, revealing potential vulnerabilities for a general-election presidential contest more than a year away.

The good news for her in the poll: Clinton continues to lead the Democratic field by more than 30 points, and the favorability numbers for two of the top Republicans are even worse than hers.

Just 37 percent of all Americans have a positive view of Clinton, versus 48 percent who have a negative view (-11).

That’s a sharp drop since June, when the NBC/WSJ poll showed her with a 44 percent positive, 40 negative rating (+4) – so an overall 15-point swing.