DES MOINES, Iowa — While his crowd sizes are underwhelming, Joe Biden is hoping veterans, Catholics and people of color will be his secret weapons in the upcoming Iowa caucuses, according to three people who attended a private donor retreat here and were briefed on the plan.

The campaign has taken some unusual steps to reach those voters, who are more typical of general-election swing voters than the Democratic Party loyalists who generally turn out in primaries and caucuses.

For instance, Biden officials told donors the campaign has hired paid canvassers, instead of relying solely on volunteers, to reach the state's small but growing population of Latinos and African Americans. Iowa Democrats not affiliated with the campaign say that's unusual, since the state’s first-in-the-nation caucuses, now just over a week away, are often about showcasing grassroots enthusiasm.

The campaign has also had nuns send handwritten letters to Roman Catholics, focusing on Dubuque, a heavily Catholic city, attesting to Biden's faith, which he's spoken about on the trail. And it's focused on targeted rural areas, including on a bus tour with the former vice president, where few delegates are at stake, but they can sometimes be won by persuading just a handful of caucusgoers.

To find veterans, the campaign pulled county property tax records, since they qualify for a tax credit, and then invited them to events with prominent Biden supporters who are also veterans, such as former Secretary of State John Kerry and freshman Rep. Conor Lamb, who has told Iowans that Biden can win back places like his western Pennsylvania district, which went for Donald Trump in 2016.

The donor retreat, which was held last weekend at the Marriott hotel in downtown Des Moines, offered a chance for members of Biden’s national finance committee to hear from top campaign officials, including the vice president himself, and for wealthy supporters to get a taste of canvassing door-to-door in their fancy ski gear in 6-degree temperatures.

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Campaign manager Greg Schultz and chief analytics officer Becca Siegel walked donors through their national strategy, and how Iowa fits into it, while Iowa State Director Jake Braun spoke about the state’s Feb. 3 caucuses.

Publicly, the campaign has downplayed the importance of Iowa in Biden's path to the nomination, especially after a weak showing in a recent poll, noting he is expected to do well in more diverse states down the road, such as South Carolina.

But the presentation to donors made it clear they still view Iowa as essential, if less critical than it might be to other candidates, since they believe they have other pathways to the nomination.

And they said managing expectations in Iowa was key to their plan of trying to build a sense of momentum heading into Super Tuesday on March 3, when more than a dozen states will vote on the same day.

The campaign brass said they had simulated some 10,000 possible routes through the primary calendar to gauge how important each state is and, not surprisingly, found that a vote in Iowa was worth more than a vote anywhere else, since success in Iowa helped in each subsequent state.

Some of Biden's events have been relatively sparsely populated, even in the run-up to the Iowa caucuses, especially considering he’s still the race’s front-runner in national polls.

For instance, while former Mayor Pete Buttigieg, of South Bend, Indiana, packed some 1,200 into an event in Cedar Rapids on Tuesday night, there were only several dozen at a Biden town hall in Mason City the next morning.

But Biden's strategy was evident on his most recent swing through some of the state’s smaller cities, which included a national security event at a Veterans of Foreign Wars post and pitches about his electability to voters in redder parts of the state.

Christie Vilsack and her husband, former Iowa governor and Obama Agriculture Secretary Tom Vilsack, have endorsed Biden, urged Iowans to "think of your favorite Republican ... because we all have Republican friends."

"I’m urging all of you to make that practical decision," Vilsack said.

Randy Flaherty, a disabled Navy veteran who has two sons in the military, met Biden during his 2008 presidential run and carries in his wallet a challenge coin the former vice president gave him.

"I think he's the only candidate that we've got running, and I've talked to about all of them, who can put this country back together," Flaherty said.