Former Vice President Joe Biden at a campaign rally last...

Former Vice President Joe Biden at a campaign rally last week in Mason City, Iowa. Credit: AP / Charlie Neibergall

The time for fretting over campaign conduct ended three years ago when Donald Trump saw his insult-comic behavior rewarded with his election as president.

So there's an impulse to say it was no big deal when Democratic contender Joe Biden snapped at an Iowa man who accused Biden of getting his son Hunter a job with a Ukrainian gas company in exchange for access to the Obama administration.

"You're a damn liar, and that's not true," Biden said, challenging him to go one on one physically and mentally. Some heard the former vice president call the man "fat" at one point, though Biden insists he said "facts."

What's striking is Biden's confronting his accuser up close and in real time. The over-the-top readiness to rumble came off as something different from the Trump style of demonizing faraway foes on Twitter and at fan rallies.

Biden had a fairly extended exchange as such things go.

The man, an 83-year-old Iowa farmer, began by saying he thought Biden was too old for the job of president. After a back-and-forth, the farmer said: “It looks, it looks like you don’t have any more backbone than Trump does."

Biden said to the crowd: “Any other questions?”

“Yeah, all right. I’m not voting for you,” the man said.

“I knew you weren’t, man," Biden said.

The man, however, said later that he still might vote for Biden if he's the Democratic nominee.

By contrast, Trump often doesn't even confront subordinates before firing them, but he does name-call rivals and perceived enemies and plays on their physical attributes.

Even as he faces impeachment, Trump has to be considered the front-runner in next year's election. This would be true of any president seeking a second and final term. Economic and employment numbers are up and so far he hasn't started any new wars.

Can Biden's defensiveness, excitability or near-constant verbal gaffes be said to matter at this time in the divided national political culture?

Do the ambitious details of Sen. Liz Warren's Medicare proposal, or Mike Bloomberg's fortune, or Trump's lack of regular manners determine their electoral fates?

Earlier in the decade, those questions might have seemed easier to answer. This time out, the rewards of controversial behavior are hard to predict.