LAS VEGAS — The Nevada caucuses are shaping up as a potential firewall for Joe Biden if the first two 2020 Democratic nominating contests don't go his way.

Polling ahead of the Feb. 22 caucuses is the most positive for the former vice president and Delaware senator in months, giving him a boost as he campaigns in Nevada on Tuesday. The Nevada campaign swing comes as polls in Iowa, hosting the kick-off Feb. 3 caucuses, and New Hampshire, with its Feb. 11 primary, show Biden, 77, in a dogfight with top-tier rivals Bernie Sanders, Elizabeth Warren, and Pete Buttigieg.

Nevada offers Biden an opportunity to win new converts to his cause. Iowa and New Hampshire have relatively stable populations, and many voters recall Biden's visits going back to his first of three presidential bids, in 1987. Nevada is full of transplants, including a significant immigrant population, and each of the front-runner campaigns are focused on attracting new voters there.

And though Nevada is third on the Democratic presidential primary calendar, Democrats often feel their state is left out of the national conversation. After all, it boasts one of the nation's most diverse electorates, with Latinos comprising roughly 30% of the population. Also, unions arguably are more influential in Nevada than any other state, with the service sector dominating the Las Vegas economy.

It's also where, aside from South Carolina, the former vice president has seen his most consistent and positive polling.

Nevada has gained a reputation of being notoriously hard to poll, because 80% of the state lives in Clark County, home of Las Vegas, where many workers have unusual shifts. What surveys exist show Biden remaining the favorite to win the state's caucus since polling began in March.

As the race currently stands, Biden leads the pack with 29% support, according to a RealClearPolitics average of mainstream polls. Warren and Sanders, senators from Massachusetts and Vermont, respectively, are in a statistical tie for second with 20% and 19.8%.

A CBS/YouGov survey released in November found Biden's support as high as 33%, with Sanders in second place at 23%.

Those numbers closely mirror Biden's standing in South Carolina, the fourth primary state, on Feb. 29, which is also home to one of the most diverse Democratic primary electorates.

According to a RealClearPolitics average of polls in South Carolina, Biden has more than double the support of second-place challenger Warren. Biden currently receives 35.3% of the vote compared to Warren's 16.3% and Sanders's 12.8%.

A CBS/YouGov survey released last month found that as many as 45% of South Carolina's Democrats support Biden's candidacy, with 17% supporting Warren.

For months, particularly as their numbers began slumping in Iowa and New Hampshire, Biden's team told donors and reporters that it could rely on South Carolina for a much-needed win heading into Super Tuesday, on March 3.

And the positive Nevada numbers come at a helpful time for Biden's campaign. The former vice president continues to be confronted with questions about the work of his son, Hunter Biden, for Ukrainian national gas company Burisma. The board membership came during the Obama administration, when Joe Biden's office was overseeing Ukraine policy. The issue has become a flashpoint in House Democratic impeachment proceedings against President Trump, with Republicans pointing to Hunter Biden's Ukraine work as inherently corrupt.

In Nevada, Hispanic supporters are key for Biden. Former Secretary of State Hillary Clinton, the establishment favorite in 2016, won the state's caucuses with 52.64% support, thanks to overwhelming support from the Hispanic community.

On Monday, Tuesday, and Wednesday, Biden, Sanders, and Warren will court members of the Culinary Workers Union, which is hosting a presidential forum in Las Vegas.

Winning organized labor is crucial to securing a win, with Nevada having the 12th highest proportion of unionized workers in the country and among the most politically influential.

Behind the scenes, winning the support of former Senate Majority Leader Harry Reid may prove even more valuable. Those close with Reid have told the Washington Examiner the Nevada Democrat, who retired from the Senate in 2017, expressed surprise at Warren's continued defense of "Medicare for all." Warren's poll numbers fell as she sought to explain how to pay for the program, which would effectively end private health insurance in favor of a government program.

Reid, who is credited with building a Democratic political machine in the state over more than 50 years, has signaled he is ready to put his finger on the primary scale.

“I think that we should focus on improving Obamacare. We can do that — without bringing something that would be much harder to sell,” Reid said in August. “Improving Obamacare: People understand that. They would appreciate that. It locks in many important things.”