Joe Biden has a major problem. Even among voters who support him, there is a complete lack of enthusiasm. People like him and everyone knows his name. Good old Joe has been around Washington forever and by virtue of that, people appear to trust him more than say a Kamala Harris or a Corey Booker. But try as he might, he cannot seem to energize his base.

Patrick Murray, director of the Monmouth University Polling Institute, recently told the New York Times, “I did not meet one Biden voter who was in any way, shape or form excited about voting for Biden.”

Murray added that, “They feel that they have to vote for Joe Biden as the centrist candidate, to keep somebody from the left who they feel is unelectable from getting the nomination.”

Even Biden’s wife, Dr. Jill Biden, made this argument last week in New Hampshire. She told voters:

You know you may like another candidate better but you have to look at who’s going to win…. So yes, you know, your candidate might be better on, I don’t know, health care than Joe is, but you’ve got to look at who’s going to win this election, and maybe you have to swallow a little bit and say, ‘Okay, I personally like so-and-so better,’ but your bottom line has to be that we have to beat Trump.

The New Republic’s Alex Shephard has published a piece entitled “Is the Biden Bubble About to Burst?” in which he argues that Biden’s “electability” pitch is “losing its luster.” Shephard acknowledges that Biden has a commanding lead in all of the polls. But, he says, “that lead may be illusory. There’s a growing sense that Biden is something of a starter nominee, a candidate that voters can glom onto while they search for someone who better suits their values.”

Now that voters are getting to know the candidates a bit better, the issue of electability is less important. That’s why we’re seeing Elizabeth Warren and Bernie Sanders moving up in the polls. “Both candidates have used policy as the backbone of their campaigns, and both have large and deeply loyal bases.” Other candidates who haven’t been able to fall back on their ability to beat Trump have been busy coming up with ideas and proposals which have excited Democratic voters, while Biden has stood still. And they are beginning to see results.

At a campaign event in Iowa last week, Biden was asked by Fox News’ reporter Peter Doocy if he was concerned to see Sen. Elizabeth Warren draw a 12,000 person crowd on Monday in Minneapolis. The former vice president replied, “It depends on what the nature of the event is. What I’m trying to do is go around from town to town, and I’m drawing as big a crowd or bigger than anybody. Have you seen anybody draw bigger crowds than me here in this state?”

“Yes,” Doocy answered.

Biden asked, “Oh, you have? Where?”

Doocy replied, “Des Moines.”

The political world is starting to notice that a shift is taking place among the candidates in the Democratic primary.

JoAnn Hardy is the Democratic Party chair for Cerro Gordo County, Iowa. She said of Biden that “he’s doing OK, but I think a lot of his initial strength was name recognition. As the voters get to meet the other candidates, he may be surpassed soon. I would not be surprised.”

Shephard writes:

It is an explicit play it safe approach and one aimed at Democrats who are concerned big policy ideas will alienate general election voters. This is not exactly the stuff of which inspiring campaigns are made. It’s condescending at best—existential policy imperatives like climate change and health care are hardly trivial, regardless of who occupies the White House—but it also contains an air of menace. Biden and his supporters are trying to create a binary choice: Vote for Joe and beat Trump, or don’t vote for Joe and lose. But most early polling has suggested that any candidate with near-universal name recognition—something that would automatically follow a major party presidential nomination—would lead Trump in a head-to-head competition.

Did Biden really believe he could simply coast to the nomination on the electability issue? Did he think that all he needed to do was just show up for a few rallies without even having done the work of putting together a platform of policy proposals? It would appear so.

In the last few months, Biden has actually given Democratic primary voters many reasons not to vote for him. In addition to his clumsy flip flops on issues such as the Hyde Amendment, he seems to commit a new gaffe every time he appears at a campaign event.

And sadly, it’s becoming apparent that age is starting to take its toll on him. This, I think, may become his biggest roadblock to the nomination.

Speaking to the press last week in New Hampshire, a reporter said that some voters are concerned about his age, to which he replied, “I say if they’re concerned, don’t vote for me.”

In the very near future, Biden may indeed learn that the electability argument will only carry him so far. And as Shephard suggests in his article, Biden’s bubble may be about to burst.