TOM LEONARD: So can they topple Sleepy Joe - and who should replace him?

After the horror, the hope. As Democrats digest the true awfulness of Joe Biden's performance in Thursday night's presidential debate, talk has inevitably turned to an equally compelling topic: who might replace him and perhaps snatch victory from Donald Trump on November 5?

However, Plan B is not without its complications.

No serious Democrat candidate has yet stepped forward to challenge Biden, the sitting President, and the obvious contenders are all still publicly pledging loyalty to him.

There's no time to hold new Primary selection ballots. Besides, Democrats have been through the process already and chose Biden as their candidate.

Under party rules, delegates to the Democratic National Convention in Chicago in August (where the party's presidential candidate is formally nominated) remain bound to support him – unless Biden himself announces that he's leaving the race.

The Convention would then assume responsibility for voting on an alternative, of which there are plenty of options. Biden is notoriously stubborn, however, and ominously told supporters, 'Let's keep going', shortly after limping off the debate stage in Atlanta.

Party insiders believe First Lady Jill Biden could play a crucial role in persuading her husband to bow out.

His former boss Barack Obama (Biden was his vice president) might also be called on to nudge him in that direction.

And were he to voluntarily step aside at the party convention, allowing a completely fresh vote, the Democrats would avoid having to accept Vice President Kamala Harris as Biden's automatic successor.

A number of pundits have argued that bypassing a black woman would cause an enormous stink among some Democrats.

But the general view is that letting her be the candidate makes absolutely no sense and would be virtually guaranteed to hand victory to Trump.

The deeply unimpressive 'Veep' has even worse approval ratings than Biden.

If not Kamala, then, who might save the day for the Democrats?

Here are some of the names cropping up most frequently:

GRETCHEN WHITMER

The 52-year-old governor of Michigan's name heads many Democrat wish-lists after making the shortlist of Biden's potential running mates in 2020.

Widely popular in the swing state, she is a moderate who has risen fast through the party.

'That woman in Michigan', as Trump describes her, is a former prosecutor and mother- of-two who supports stricter gun laws and the repeal of abortion bans.

In 2020, the FBI famously thwarted a plot by a Right-wing militia group to kidnap Whitmer after she antagonised conservatives with her tough response to the Covid pandemic.

She has a memoir coming out next month which some cynically believe was timed perfectly for a possible presidential run.

She often seems refreshingly normal. Talking about her childhood earlier this week, Whitmer admitted she once got so drunk that she threw up over her high school principal. 'Not my best day,' she admitted.

GAVIN NEWSOM

Often mentioned in the same breath as Whitmer, the smooth and telegenic governor of California has considerably more baggage, however, and some pundits believe that rules him out.

First there's Newsom's track record in the 'Golden State', where he has presided over a huge budget deficit.

Crime and homelessness are devastating cities such as San Francisco and Los Angeles. And he's far too woke for the rest of the United States, say critics.

Then there's his colourful personal history. Newsom, 56, hails from California aristocracy and, as mayor of San Francisco, once sprawled on a silk rug with his first wife Kimberly Guilfoyle (now fiancee of Donald Trump Jr and a Trump campaign stalwart) for a glossy magazine photoshoot.

In 2007, Newsom admitted he had a drink problem days after it emerged he'd had an affair with the wife of his best friend and campaign manager, destroying his friend's marriage.

He married Jennifer Siebel in 2008 and they have four children.

His past behaviour is not going to impress voters if he comes under intense media scrutiny as a White House candidate.

J.B. PRITZKER

Another state governor, this time of Illinois, Pritzker, 59, is a venture capitalist billionaire.

He is also heir to the Hyatt Hotel fortune and so has the considerable advantage of being able to sink a lot of money into a presidential campaign. But in other areas, he hardly has the sparkle of rivals such as Whitmer or Newsom.

He legalised recreational cannabis, declared Illinois a 'sanctuary state' for women seeking abortions and has overseen a ban on assault weapons – all solid, if predictable, Democrat goals.

In 2018, a Chicago newspaper revealed that Pritzker had removed all the toilets from a mansion he'd bought next door to his home, making it technically 'uninhabitable' and thereby qualifying him for a valuable property tax reduction.

JOSH SHAPIRO

A rising party star, the governor of Pennsylvania, 51, is one of the moderate Democrat politicians who many pundits believe are best placed to challenge Trump.

A conservative Jew who observes the Sabbath and keeps a kosher kitchen, Shapiro has the advantage of having been an effective steward of a crucial 'battleground' state.

A recent poll revealed that more than three in 20 Trump supporters said they actually like him.

He's also a strong debater but, like some of the other governors who could be in contention, he lacks nationwide recognition. Barring a sudden influx of donations, Shapiro is also missing the cash needed to run a strong presidential campaign.

What's more, he's only been a state governor for a year and a half. Some pundits believe he's more of an option for the 2028 election.

ANDY BESHEAR

With so few undecided voters left, a candidate capable of winning over supporters of the rival party could be crucial come November. Step forward Andy Beshear, who has twice managed to become Democrat governor of the deeply Republican state of Kentucky – which is no mean achievement.

One of America's most popular governors, he's less well-known than anyone else on this list and, at 46, might be seen to lack experience.

Even so, at least one Democrat donor was yesterday singling him out as a potential Biden successor.

The apparently clean-cut lawyer, who serves as a church deacon, along with wife Britainy, is a diehard moderate and recently launched a political action committee to support candidates who eschew 'the politics of anger, division and hate'.

But there are questions as to how much he actually wants to be President and how much Left-wing Democrats would warm to him.

As a Washington Post columnist observed: 'He is either very sincere, kind and nice – or fakes all of that extremely well.'