Former vice president and 2020 Democratic presidential candidate Joe Biden taks a selfie attendees during a campaign event on June 11, 2019 in Davenport, Iowa.

Two dozen Democratic presidential candidates have swarmed early 2020 primary nominating states to build support, but one candidate has consistently found himself ahead of the pack.

Former Vice President Joe Biden has led or tied for the top spot in every major poll of Iowa, New Hampshire, South Carolina and Nevada so far, according to surveys tracked by RealClearPolitics.

The latest poll came Wednesday: Biden garners support from 36% of likely Nevada Democratic caucusgoers, followed by 19% for Sen. Elizabeth Warren, D-Mass., 13% for Sen. Bernie Sanders, I-Vt., 7% for South Bend, Indiana, Mayor Pete Buttigieg and 6% for Sen. Kamala Harris, D-Calif., a Monmouth University survey found.

The result largely reflects other polls in the four early nominating states. Biden and Sanders have enjoyed a cushion over their competitors in an average of surveys in Iowa, New Hampshire and South Carolina. But Warren's 19% of support in Nevada stands out, because it ranks as easily her best performance in an early-state poll.

Strong showings in the four states can not only start the process of racking up delegates but also help candidates unlock donations and media coverage that propel them to later success. Factors from campaign strategy to demographics or even a candidate's home state can lead to drastically different results across the first four voting states.

Warren's already-sprawling policy platform — which broadly relates to reining in big corporations and boosting workers — "may be a good fit" for Nevada's "highly unionized service sector workforce," Patrick Murray, director of the Monmouth University Polling Institute, said in a statement. But the senator is "nowhere near the top tier" among Latino and black voters, who make up a "significant part" of the Democratic base in the state, Murray added.