WASHINGTON — The leading Democratic presidential contenders have begun criticizing Joseph R. Biden Jr. for, among other things, being too old, too moderate, too fixated on President Trump and too delusional about the state of the Republican Party. But you’d be forgiven if you missed it, because they almost never mention Mr. Biden by name.
Welcome to the season of the velvet fist.
As the first Democratic debate nears, and Mr. Biden carefully nurtures his lead in the polls, his opponents have begun the delicate footwork of going on the attack without appearing as the aggressor. Turning to euphemisms, translucent critiques and at times all but winking, they are hoping the voters and news media will pick up on their implicit message in a way that doesn’t also sully them in the process.
Even serious firestorms seem to fail to land a direct hit on Mr. Biden, the former vice president. When his campaign said on Wednesday that he still supported the Hyde Amendment, which bans the use of federal funds for abortions in most cases, a wave of condemnation arose on the Democratic left, and the leading candidates scrambled to state their opposition to the measure. But there was one word missing from nearly all their denunciations: Biden.
For the rest of the field, Mr. Biden is akin to Lord Voldemort, a rival whose name they dare not speak.
(Mr. Biden reversed his support for the Hyde Amendment on Thursday evening.)
Campaigns have their own cyclical rhythm, and, despite the heavy interest from activists, it is still early to turn fully negative against an opponent. Moreover, many in the rank-and-file are consumed with ousting Mr. Trump and may not respond well to intramural hostilities.
“If we can’t get along, we’ll never win the general election,” said Jeremy Dumkrieger, the Democratic Party chairman in Woodbury County, Iowa. Mr. Dumkrieger hosted a cookout Saturday at his Sioux City home for local presidential campaign staffers as part of his effort to foster collegiality.
Perhaps most of all, though, the restraint owes to a fear rooted in campaign precedent: When one candidate attacks another in a multicandidate primary, it usually redounds to the benefit of a third. Just ask John Kerry, who surged in Iowa ahead of the 2004 caucuses there after a pair of his rivals clashed.
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The Democratic field is so vast, and the thirst for media attention so immense, that one of the candidates may soon mount a frontal assault against Mr. Biden. Senator Bernie Sanders of Vermont, for one, briefly criticized him by name over trade and foreign policy when Mr. Biden first entered the race.
The bank-shot broadsides on Mr. Biden can be traced as far back as when Senator Elizabeth Warren of Massachusetts went to Iowa in January and recalled that her political awakening began with her opposition to a bankruptcy bill that Mr. Biden helped shepherd through the Senate in 2005.
They have intensified in recent weeks, as it has become clear the former vice president’s advantage in the polls is not dissipating, and reached new heights last weekend at the California Democratic convention, when some of the top candidates used their time on stage to test out implicit lines of attack.
“When the future of the planet is at stake, there is no ‘middle ground,’” Mr. Sanders said at the convention. He reprised the “middle ground” language to lay out his progressive agenda on a number of issues — not-so-subtly chiding the Biden adviser who suggested to Reuters last month that the former vice president would seek a “middle ground” on climate issues.
“Some say if we’d all just calm down, the Republicans will come to their senses,” Ms. Warren said when it was her turn at the microphone in San Francisco, an obvious reference to Mr. Biden’s prediction that the Republican Party would have “an epiphany” after Mr. Trump was out of office and agree to work with Democrats. (During a Wednesday night town-hall event on MSNBC, Ms. Warren passed on two chances to name Mr. Biden when discussing her differences with him.)
Senator Cory Booker of New Jersey got in a twofer at the convention, warning Democrats that “this is not a time for a savior” and that defeating Mr. Trump should be “a floor, not a ceiling.” The first allusion was to the party’s hopes that Mr. Biden is the safe choice to defeat Mr. Trump, and the second was to the former vice president’s overriding focus on ousting the president.
And Pete Buttigieg, the mayor of South Bend, Ind., trod the same beating-Trump-isn’t-enough ground, though with the generational twist. “There’s no going back to normal right now,” said Mr. Buttigieg, who, at 37 years old, is nearly four decades younger than Mr. Biden. “Democrats can no more promise to take us back to the 2000s or 1990s than conservatives can take us back to the 1950s.”
Few candidates in the race have gone so far to draw an unsubtle contrast with Mr. Biden as Mr. Buttigieg. He often talks about how he’ll reach Mr. Trump’s current age, 72, in 2054 (without mentioning that Mr. Biden is, at the moment, 76) and sells “Win The Era” campaign merchandise.
But when these candidates are pressed about whether they’re confronting Mr. Biden, they only elevate their gamesmanship.
By Monday night, when Mr. Buttigieg reached for his return-to-normalcy critique during an otherwise friendly MSNBC town hall-style interview, the moderator, Chris Matthews, cut him off.
“That’s what Biden wants,” Mr. Matthews said. “You’re suggesting Biden would do that.”
“I’m not going to talk to anybody else’s campaign strategy,” Mr. Buttigieg replied.
Mr. Booker similarly avoided specifics last month in Iowa after testing out his line about not seeking “a savior” and criticizing the 1994 crime bill that Mr. Biden sponsored.
“I’ve got nothing to say negative about Vice President Biden,” Mr. Booker said in a brief interview.
While the Democratic candidates tread lightly around their Biden critiques, a less polite offensive against the former vice president is being mounted online by committed activists from the party’s left wing.
“People will take every opportunity to share any meme that is anti-Biden,” said Sara Riley, a lawyer from Cedar Rapids, Iowa, who is volunteering for Mr. Biden’s campaign. “They are not sharing memes that denigrate Seth Moulton.”
It is easy to understand both the temptation and the caution.
Mr. Biden is a useful foil to Mr. Sanders on ideology; to Ms. Warren on ideology and on some of the process issues that animate liberal activists; and to Mr. Buttigieg on age.
For many of the other candidates, taking on Mr. Biden represents an opportunity to break through a field of nearly two dozen candidates.
And as a bonus, Mr. Biden has pledged not to fire back at fellow Democrats, leaving the attacks unanswered.
But to be the first Democrat who unambiguously lights into Mr. Biden is to invite considerable risk. Just ask the aides who were on both ends of some of the most memorable attacks in presidential primary history — attacks that ended with political murder-suicide.
Three years ago, in the Republican primary, Senator Marco Rubio of Florida came out of the Iowa caucuses with a solid third-place finish and hopes of emerging in New Hampshire as the establishment-aligned alternative to Mr. Trump and Senator Ted Cruz of Texas.
Then former Gov. Chris Christie of New Jersey used a nationally broadcast debate to savage Mr. Rubio as a mediocrity who simply mouthed the rehearsed lines his staff fed him — to which Mr. Rubio responded by repeating the same lines.
The back-and-forth dominated the final days of the New Hampshire primary, which Mr. Trump handily won. And it all but ended any hopes Mr. Rubio (who came in fifth) and Mr. Christie (who came in sixth) had in the state.
“You expose voters to negative information about an opponent, but the problem is that voters also tend to punish the attacker,” said Todd Harris, a Republican strategist who worked for Mr. Rubio.
Being viewed as a candidate on the attack is a particularly dangerous attribute in Iowa, where Democrats still feel reverberations from the 2004 and 2016 contests.
In 2004, Mr. Kerry won Iowa after the early favorite in the state, Richard A. Gephardt, and a liberal insurgent, former Gov. Howard Dean of Vermont, spent the final weeks blasting each other.
“The potential problem is people throw up their hands and say, ‘Of the two people who are attacking each other, I don’t like either one of them,’” said Steve Elmendorf, who was chief of staff for the Gephardt campaign. “They go to a third option.”