Robert Schmuhl: 'Biden must prove he can KO bruiser of a president'
Though Democrats in the US won't begin casting ballots for a 2020 presidential nominee until February, they've spent this summer sizing up the two dozen candidates fighting a daily battle to reach next year's ultimate bout against Republican heavyweight Donald Trump.
As the consistent front runner, Joe Biden has become something of a human punching bag in these fisticuffs of American politics.
When the two-term vice president announced his run for the White House in late April, a CNN survey of Democrats and Democratic-leaning independents counted 39pc of respondents in his corner. By the end of June, that number had dropped to 22pc, and most recently (by averaging several polls) less than a third of those asked favour Mr Biden.
Called by 'Time' magazine "the most fragile front runner in a generation", Mr Biden finds himself forced to defend his governmental record, his stance on issues or his status as a septuagenarian at every event.
The process has played out most visibly for millions in televised debates at the end of June and July. Each month, 20 candidates - divided in half over two nights - have tried to make their case while bruising their opponents.
During Mr Biden's first round in June, Senator Kamala Harris of California, a woman of colour, landed several blows, especially discussing race relations and her opponent's long-ago association with segregationist Southern legislators.
Many observers came away from these exchanges wondering whether the 76-year-old former vice president and senator could withstand the rigours of an 18-month campaign that will include relentless assault from that noted Twitter pugilist Mr Trump.
Ms Harris exposed vulnerabilities in Mr Biden's record, which extends back to 1972 when he was first elected to the Senate, an office he held 36 years. Add eight years as Barack Obama's Number Two (2009 to 2017), it totals 44 years of Washington service.
Other candidates are combing through every vote he cast and each statement he made to find stands he previously took that might weaken Mr Biden and strengthen their positions. That's how a multiple-round championship fight for the White House is conducted.
Ms Kamala, a first term California senator, emerged from the June debate as one of the top candidates in this crowded field.
She didn't do nearly as well in July when she confronted Mr Biden in a re-match, but her performance will keep her in the first tier of likely nominees. Along with Mr Biden and Ms Harris, senators Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts now occupy the uppermost places among the aspirants grappling for support and attention.
Both Mr Sanders and Ms Warren bolstered their standing as potential party standard bearers during their most recent debate in Detroit. In each case, these East coast senators advocated more liberal proposals for government policies, especially in the realms of health care, immigration and climate change. (Ms Harris is on the left of the political spectrum - but not to the degree of either Mr Sanders or Ms Warren.)
What's shaping up for the fall rounds of this ongoing brawl is an intraparty free-for-all pitting moderate Democrats, represented most notably by Mr Biden, against avowedly leftist contenders for the nomination: Mr Sanders, Ms Warren and, though less so, Ms Harris and senator Cory Booker of New Jersey, among others. In shorthand, "the realists" vs "the revolutionaries".
For rank-and-file Democrats surveying the prospects, two cardinal concerns frame their choice. They want the man or woman with the best chance - and iron chin - to take on Mr Trump, and they yearn for someone who espouses their thinking.
In others words: Who's most electable, and whose agenda is more agreeable?
Many Democrats fear nominating a candidate perceived as too far on the left will scare off more centrist, independent voters in the election come November of 2020.
Republicans are already planting seeds that whoever leads the opposition next year will be a wild-eyed radical.
Without any foundation, Mr Trump announced to reporters at the G20 conference in Japan a few weeks ago: "There's a rumour the Democrats are going to change the name of the party from the 'Democrat Party' to the 'Socialist Party.'"
That rumour, no doubt, started with the president himself or an adviser, but it raised a warning flag of what Democrats can expect whenever their nominee gets in the ring against a no-holds-barred battler.
Mr Biden is the strongest centre-left candidate. However, he'll need to aggressively defend his nearly half-century in Washington - increasingly referred to as "the swamp" by three-quarters of Americans who mistrust the ways and wiles of the nation's capital - and his age. If elected, he'd be 78 entering the White House.
The next debate among candidates won't take place until mid-September and requirements for participation - judged by performance in opinion polls and raising money across the country -are more demanding than the first two. A winnowing to eight or 10 viable competitors will concentrate the public mind, giving sharper definition to the contest.
At the June debate when he was on the ropes, Mr Biden unexpectedly cut off one of his responses by saying: "My time is up."
The next few months will tell all of us whether what seemed an odd, almost throwaway line becomes a prediction about the fight of this Irish American's political life.
Robert Schmuhl is professor emeritus of American Studies at the University of Notre Dame and an adjunct professor in the School of Law and Government at Dublin City University