Democratic front-runner Joe Biden Joe BidenBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Democratic groups using Bloomberg money to launch M in Spanish language ads in Florida Harris faces pivotal moment with Supreme Court battle MORE has an unusual advantage in the 2020 race: the sheer size of the field.

The former vice president has leapt out to a wider lead than many pundits expected since launching his bid in late April.

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On Tuesday afternoon, he had about 35 percent support nationally according to the RealClearPolitics polling average — a roughly 2-to-1 advantage over his nearest challenger, Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (I-Vt.).

Beyond that, 22 other candidates are vying for every vote. The basic math helps Biden, party insiders say.

“I think it’s a very big advantage, beginning in Iowa where you have to get 15 percent [of caucusgoers] to qualify for delegates,” said veteran Democratic strategist Tad Devine. “If you are able to have solid support of about one-third of the vote, it’s very hard to stop a front-runner.”

Devine, who worked for Sanders’s 2016 presidential campaign but is not affiliated with any candidate this cycle, contrasted Biden’s position as a front-runner against that of strong favorite — and eventual nominee — Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE four years ago.

“If you’re the front-runner and there is only one serious alternative, which is what happened in 2016, you can have a 40- or 50-point lead and lose it,” Devine said. “But if you have a lot of candidates and you have somebody with a significant base of support that doesn’t erode … it’s very hard to beat a candidate like that.”

Another unaligned Democratic strategist, who requested anonymity to speak candidly, argued that the big field aids Biden in part because he is the best-known contender: “The reality is that, when you flood people with this many choices of candidates who are not well-known, it is going to naturally help the front-runner because they can’t settle on one candidate.”

It’s not just the number of candidates that puts a wind at Biden’s back. Many of his most serious rivals are competing with each other for specific swaths of voters.

Sanders and Sen. Elizabeth Warren Elizabeth WarrenDimon: Wealth tax 'almost impossible to do' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context Democrats shoot down talk of expanding Supreme Court MORE (D-Mass.), for example, are both favorites of progressives. There is some evidence that recent progress in polls for Warren is coming at Sanders’s expense. The two are even competing for approval from other leading lights of the left. Rep. Alexandria Ocasio-Cortez Alexandria Ocasio-CortezWells Fargo CEO issues apology after saying there was a 'limited pool of Black talent' Brand responds to Trump claim protesters throw tuna cans at police: 'Eat em, don't throw em' CNN's Don Lemon: 'Blow up the entire system' remark taken out of context MORE (D-N.Y.) has joined Sanders in pushing legislation aimed at curbing the power of credit card companies, but she has also appeared in short videos, posted to Twitter, with Warren.

Democratic voters who are eager to see a female nominee have both Warren and Sen. Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (D-Calif.) among the top tier of candidates, as well as other possibilities such as Sens. Amy Klobuchar Amy KlobucharSocial media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight Sunday shows - Ruth Bader Ginsburg's death dominates MORE (D-Minn.) and Kirsten Gillibrand Kirsten GillibrandSunday shows preview: Justice Ginsburg dies, sparking partisan battle over vacancy before election Suburban moms are going to decide the 2020 election Jon Stewart urges Congress to help veterans exposed to burn pits MORE (D-N.Y.).

The splits and intraparty rivalries can cut across racial and economic lines, too. The presence of two major black candidates, Harris and Sen. Cory Booker Cory Anthony BookerBipartisan praise pours in after Ginsburg's death DHS opens probe into allegations at Georgia ICE facility Democratic lawmakers call for an investigation into allegations of medical neglect at Georgia ICE facility MORE (D-N.J.), could prevent African American support coalescing behind either one. Former Rep. Beto O’Rourke (D-Texas) and South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegThe Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice Hillicon Valley: FBI, DHS warn that foreign hackers will likely spread disinformation around election results | Social media platforms put muscle into National Voter Registration Day | Trump to meet with Republican state officials on tech liability shield MORE (D), both lean heavily on support from upscale white voters.

By contrast, Biden’s niche — relatively moderate, purportedly electable, popular with older voters — is not particularly crowded.

Klobuchar perhaps comes closest to a Biden-like appeal, but she is running at about 2 percent support nationally, according to the RealClearPolitics average.

Still, while few dispute that the large field helps Biden, some argue he should enjoy it while it lasts — which may not be for long.

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Several sources pointed, unprompted, to the release of fundraising totals for the second quarter, which ends June 30, as a potential watershed moment, demonstrating which candidates can mount a serious challenge and which cannot.

The first debates, set for June 26 and 27 in Miami, may give some long-shot candidates a chance to break out, but they could also spell doom for those who don’t make an impact.

The huge field could thin out soon enough.

Perhaps unsurprisingly, it is voices from the left of the party who are forcefully urging people not to get carried away about Biden’s lead 250 days before the Iowa caucuses.

“In a field like this, with a clear, early front-runner — not to mention one who is so out of step with so much of the Democratic base — it is inevitable that the field is eventually going to winnow down,” said progressive strategist Rebecca Katz, the founder of New Deal Strategies.

“The substantial anti-Biden vote will start coalescing around a few leading challengers,” Katz added. Furthermore, she said, “even in a crowded field, candidates still rise.”

To be sure, there is history of strong early front-runners coming up short in multi-candidate fields. The most famous recent example might be Clinton’s defeat by then-Sen. Barack Obama Barack Hussein ObamaThe Memo: Trump's strengths complicate election picture Obama shares phone number to find out how Americans are planning to vote Democrats' troubling adventure in a 'Wonderland' without 'rule of law' MORE (D-Ill.) in the 2008 Democratic primaries.

Still, that was a total field of just eight serious candidates, and it had become clear even by the time of the Iowa caucuses that only three — Obama, Clinton and former Sen. John Edwards (D-N.C.) — had a serious chance of victory.

(Biden ran that year and exited immediately after getting negligible support — about 1 percent — in Iowa.)

An inexact parallel for Biden’s situation can be seen in President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE’s victory in the 2016 Republican primaries. In that instance, Trump blasted out to an early lead in a 17-person field. By the time the contest had boiled down to a handful of contenders, Trump had an impregnable lead.

Right now, Trump may be unintentionally helping Biden copper-fasten his front-runner status by attacking him. Trump repeatedly ripped the former vice president during a trip to Japan in recent days.

During a press conference with Japanese prime minister Shinzo Abe, Trump said, “Kim Jong Un Kim Jong UnSatellite images indicate North Korea preparing for massive military parade South Korea warns of underwater missile test launch by North Korea Trump says he didn't share classified information following Woodward book MORE made a statement that Joe Biden is a low IQ individual. He probably is, based on his record. I think I agree with him on that.”

Biden’s campaign hit back on Tuesday, with deputy campaign manager Kate Bedingfield issuing a statement calling Trump’s remarks “beneath the dignity of the office” and blasting him for siding “repeatedly with a murderous dictator against a fellow American and former Vice President.”

To Biden’s supporters, Trump’s attitude bespeaks fear.

And they say that, no matter how big or small the primary field, it is a well-founded fear on the president’s part.

“There are pluses and minuses,” to the size of the field, said Dick Harpootlian, a South Carolina state senator and a Biden supporter. “But [Biden] is head and shoulders, in terms of support, above everybody in the race.

“Even as it winnows down, he will become even stronger.”

The Memo is a reported column by Niall Stanage, primarily focused on Donald Trump’s presidency.