“This is prime political season in Iowa and most candidates are spending a good deal of time visiting Iowa,” said Joey Norris, the Democratic chair in Montgomery County, Iowa , where Mr. Buttigieg plans to campaign on Monday. “The Biden campaign has been notably absent.”

Now, Mr. Biden’s campaign is racing to improve his standing in the state — hosting several campaign events with the Vilsacks over the weekend, and planning an eight-day swing by bus through the state after Thanksgiving and a return later in December.

Mr. Biden’s team argues that his presence in the state is comparable to that of his rivals: The campaign claims 26 offices across the state, more than 100 staff members, and it plans to continue adding staff and resources. Senator Elizabeth Warren’s campaign claims more than 20 offices, and Mr. Buttigieg’s has 29 with more to come; both cite roughly the same number of paid staffers as Mr. Biden.

Mr. Biden’s bus tour is expected to include both town hall-style events and activities with volunteers and precinct captains, like visits to phone banks and perhaps some door knocking. The counties he will visit , many of them largely rural , are home to working-class voters who often connect with Mr. Biden, and Mr. Biden will need to overperform in those areas on Feb. 3. The campaign is also closely focused on ensuring Mr. Biden hits the threshold for accruing delegates across the state.

“We need to candidly be able to keep pace, we feel like we’re going to be able to do that,” Pete Kavanaugh, Mr. Biden’s deputy campaign manager, said. “You can tell where campaigns are focusing based on where their candidates are. And, you know, we’re going to have a pretty heavy schedule here in December, starting with the bus tour and heading into January and February.”

Mr. Biden’s team argues that the former vice president, who is stronger in later-voting and more diverse states, has been trying hard to prevail in Iowa but also sees multiple paths to the nomination. Still, some advisers and allies are aware that a poor showing in Iowa could be crushing to a campaign that is premised on the notion that Mr. Biden is the most electable candidate against President Trump. Because New Hampshire, which follows Iowa in the primary calendar, historically favors candidates from neighboring states, the pressure is on here.