A sleeping giant looms over the Democratic presidential campaign, even as excitement continues to build toward the first-in-the-nation contests in Iowa and New Hampshire.

That behemoth is Texas.

Slowly but surely, Democratic presidential campaigns are taking breaks from the early state presidential primaries and are making their cases to Texans. The March 3 Texas primary will deliver 228 delegates on a proportional basis, the third-largest delegate count of the primary season. But for now, the top priorities are clearly Iowa, which will host its caucuses Feb. 3, and the succeeding contests in New Hampshire, Nevada and South Carolina.

Candidates who place well in those states will have an opportunity to ride a wave of positive press and increased attention that could boost their campaigns — momentum that could prove more precious than those early states' delegates.

Still, Texas' large number of delegates could prove decisive, especially if the presidential campaign becomes a protracted race into the spring. And waiting until those first four states are done voting could be too late: Early voting in Texas begins Feb. 18 — only a week after the New Hampshire primary and before primary election day in Nevada and South Carolina.

“It's unlikely anyone gets to the nomination without picking up a significant chunk of delegates from Texas.” — Jesse Ferguson, former presidential campaign staffer for Hillary Clinton

“Given the number of delegates that come out of Texas, you ignore it at your peril,” said Jesse Ferguson, a former Hillary Clinton presidential campaign staffer.

"It's unlikely anyone gets to the nomination without picking up a significant chunk of delegates from Texas," he later added.

And that’s how the Texas fight will go down, by “chunks.”

A candidate could win the most votes in the state, but he or she would not necessarily win the entire 228 delegates. Instead, the state party will divvy up the delegates in a mix based on statewide performance and how a candidate fares in each of the Texas’ 31 state Senate districts. Each district will have a varying amount of delegates, based on how strong of a Democratic vote it delivered in the 2018 gubernatorial race.

And in each of these individual contests and statewide, a candidate must meet a 15% threshold to earn delegates. That means it may not be clear on election night who won the most Texas delegates.

Most top campaigns are at least staking some sort of claim on the state in three ways: seeking endorsements, making trips to the state and hiring staff.

The rush for endorsements from within the state opened up after the the departures of the two Texans in the race: Beto O'Rourke and, especially, Julián Castro. Just hours after Castro dropped his White House bid, for example, state Rep. César Blanco, D-El Paso, said he received calls from both Joe Biden's and Michael Bloomberg's campaigns.

U.S. Sen. Elizabeth Warren emerged from the Castro withdrawal with the biggest prize of all: the endorsement of him and his brother, U.S. Rep. Joaquin Castro of San Antonio.

Even as Warren earned the Castro seal of approval, a number of Julián Castro’s former backers joined last week with a long slate of previous Biden Texas supporters. His backers are beginning to mobilize in earnest; U.S. Rep. Filemon Vela campaigned with the former vice president this weekend in Nevada.

And Biden's campaign is one of several looking to influence down-ballot races: He recently endorsed Democratic candidate Eliz Markowitz in the upcoming special election runoff in state House District 28.

Meanwhile, Biden and other candidates have parachuted into the state regularly since the early days of the presidential campaign. Biden campaigned last month in San Antonio, and former South Bend Mayor Pete Buttigeig made stops last week in Dallas and Houston.

Candidate trips to Texas at this point in the cycle are nearly always tied to fundraisers, but candidates have aimed to build relationships with local officials along the way.

The exception to the fundraising tack is Bloomberg, former mayor of New York City and a billionaire who is completely self-funding his campaign. He took a bus tour of Texas over the weekend with stops in San Antonio, Austin and Dallas. Television judge Judith Sheindlin, better known as Judge Judy, who has endorsed Bloomberg, joined him.

Bloomberg has telegraphed that he will focus his national campaign on Super Tuesday states — rather than the early states in February — and Texas is no exception.

Warren is the candidate whom Democrats widely credited with the most formidable, sustained infrastructure in Texas. She has more than two dozen staffers and organizers on the ground, and every Democrat interviewed for this story pointed to her as the candidate who invested the earliest in the state. This effort includes state director Jenn Longoria, a much-envied staffer among Democratic candidates.

In the fall, Biden hired a well-regarded Dallas-based operative in Jane Hamilton, while U.S. Sen. Bernie Sanders picked up former O’Rourke spokesman Kolby Lee and boasts a strong volunteer organization.

Bloomberg, however, has launched a fourth front in this fight: television advertising. He is the only candidate who has a sustained campaign on the Texas airwaves, spending at this point about $2.7 million in ads, according to FiveThirtyEight. His vast resources allow him to play in a state where it is vastly more expensive to buy television spots. Other campaigns must weigh whether it's worth spending money to advertise in multiple television markets that are more populous than the entire state of New Hampshire, for instance.

That challenge is brewing frustration that, even despite the state’s delegate count, Texas' relevance might be lost amid the shadows of California, Iowa and other early states.

In September, Texas was at the center of the political universe as Democrats congregated in Houston for the third presidential primary debate.

"We had a moment where it felt like Texas was important to everybody, and then it slid to the back burner," said Harris County Democratic Party Chairwoman Lillie Schechter, reflecting a sentiment several other Texas Democrats shared with The Texas Tribune.

The fear is that a few weeks of television advertising and a few pit stops in the state as candidates blitz the rest of the South are not sustaining investments toward making Texas a battleground state and making progress down-ballot, like winning the state House of Representatives.

So locals are not shy about urging their national counterparts to take the state seriously — now, in February and once the primary is over.

"The decisions we make here in Texas have long-term impacts on the rest of the country," said Royce Brooks, the executive director at Annie's List, a group dedicated to electing Democratic women in the state. "We're America's policy lab, for good and for ill."

Patrick Svitek, Alex Samuels and Darla Cameron contributed to this report.