But as his rivals draw large crowds of energetic supporters in a variety of communities between the Mississippi and Missouri rivers, some of his fans worry that Biden’s decidedly more low-key approach underscores a glaring weakness: Everyone likes Joe Biden. Few seem enthusiastic about him.

“I want to see some energy going into the last four days,” said Charlie Jordan, a former backer of Beto O’Rourke who became a Biden precinct captain in Des Moines, as she waited for her candidate in a gymnasium in this suburban town. “I’m used to going to the Beto rallies where it’s super energetic.”

Biden rarely shows the same kind of energy that the former Texas congressman or other candidates bring to the stage. On Thursday, in an address meant to present a closing argument to Iowa voters, he rarely even raised his voice as he railed against Trump.

“I took on Trump all over the country, and we beat him. In fact, we beat him like a drum,” Biden said. “We’re going to beat him on the issues, flat out.”

Biden remains on top of national polls, largely on the strength of his perceived ability to best Trump in swing states.

That issue is far more important to Democratic voters than any other; in a Suffolk University poll released this week, 39 percent of Iowa Democratic voters surveyed said beating Trump was the issue most important to determining their vote, nearly double the next-highest, health care.

A CNN poll conducted earlier this month found 57 percent of Democratic respondents said it was more important to them to nominate a candidate who could beat Trump, while just 35 percent wanted a nominee who shared their views on major issues.

Biden’s campaign has leaned into his polling advantage in key states, and the perception that Republicans are afraid of him.

“Please, keep it coming — because this validation from you is the best we can get,” Mike Donilon, Biden’s chief strategist, said in a statement. “We will rally around your fear of the vice president and help as many of you as we can retire.”

Should Biden falter in Iowa and New Hampshire, South Carolina, which holds its primary on Feb. 29, is seen as his firewall, based largely on his strong backing from black voters. In the RealClearPolitics average of polling , he holds a whopping 17-point lead in the Palmetto State.

Biden’s performance in those surveys comes almost entirely on the strength of his support among the oldest Democratic voters.

In a Monmouth University poll of likely caucusgoers, Biden takes 37 percent support among voters over 65 — but just 7 perfect of the vote among those under the age of 50. Sanders, by contrast, claims 39 percent of the vote among those under 50.

To some voters, Biden’s pledge to return the country to an earlier era of political comity and calm is reassuring. A super PAC backing his campaign is running advertisements showing raging seas, casting Biden as the “president to right the ship.”

“The worst thing in our country right now is the extreme partisanship that’s going on. Joe has a proven record to reach across the aisle,” said Randy Cory, a West Des Moines resident who just retired from a career in information technology. “It’s not a strike against you, knowing what you’re doing the first day you’re in office. It should be something that’s a big plus for him.”

But to others, Biden’s decades in Washington are a potential drawback, one that sounds all too similar to the last Democratic presidential nominee who ran against, and lost to, Trump.

In a high-pressure caucus situation, when voters must publicly declare their preferred candidate among friends and neighbors, Biden’s campaign has lagged the organizational prowess of his leading rivals. His relatively late entry into the race meant many top Iowa operatives had already signed up with other candidates, and his campaign has trailed in the race to sign up local volunteers.

By contrast, Buttigieg’s campaign has trained about 5,500 precinct leaders around the state, a spokesman said Thursday, while the Sanders campaign said it would have at least one captain in each Iowa precinct — and several in big precincts expected to attract hundreds of voters.

Without a robust presence in every precinct, Iowa political observers said Biden — or any other candidate — risks leaving potential delegates on the table.

Casual or late-deciding supporters may find themselves wooed by other, better organized campaigns; backers of another candidate who is not viable in the first alignment may gravitate toward campaigns that have prepared talking points aimed at winning over late converts.

“If you don’t have people on the ground that know Iowa, then you’re at a disadvantage,” said Rob Sand, Iowa’s Democratic state auditor. “You could literally lose people because you don’t have a precinct captain.”