Biden's announcement came amid pressure by leading Democrats and donors to do so but left them with only a few weeks to the party's convention in Chicago next month, either to rally around Harris or produce alternate candidates to her in record time.
The two most recent examples in modern US history of a sitting president announcing he would not be seeking reelection to a second term were Harry Truman in 1952 and Lyndon Johnson in 1968. In both cases, they made the announcements early in the election year, leaving plenty of time for party processes and primary contests across the United States to produce the eventual candidates - who lost in both cases.
DEMOCRATS IN CONFUSION
US constitutional historian and political analyst Dan Lazare said Biden's announcement to withdraw from the election but remain in office for the remainder of his term had thrown his own party into confusion.
"The next step in the process is unclear," Lazare said. "Although second-tier Democrats are rushing to endorse Harris, the Big Four - Obama, [former House Speaker Nancy] Pelosi, [Senate Majority Leader Chuck] Schumer and [House Minority Leader Hakeem] Jeffries - are holding back."
Harris has so far failed to convince veteran party leaders that she can be an effective candidate and they are afraid a "coronation" will turn voters off, Lazare said.
So great is the confusion among the Democrats that so far there has not even been any pretense at giving the party's rank-and-file any say in whom their supposedly democratically chosen leader will be, he said.
"The people have already been shut out of the process as a few dozen mega-donors and political bigwigs tried to figure out what to do. Now they're in danger of being shut again as Democrats choose a replacement in the same closed-door manner," Lazare said.
However, this could lead to an unpredictable grassroots rebellion on the convention floor in Chicago next month, or the choice of Harris could be passively accepted after all, Lazare said.
LACK OF ENTHUSIASM
But even if Harris is accepted as the party standard bearer in Chicago without strong opposition, her lack of charisma, achievements and popular support could prove fatal to her chances against Republican candidate Donald Trump in November, Lazare said.
"Concerns over Harris's political abilities are entirely justified. Her 2020 presidential bid was so disastrous that she had to drop out in late 2019," Lazare said.
After three-and-a-half years in office with full national exposure, Harris had still completely failed to establish any convincing personal presence, he said.
"She's smarmy, the notorious Kamala cackle rubs everyone the wrong way, and, as far as I can tell, she has never had a single intelligent thing to say about any subject of political importance. She lends new meaning to the phrase 'empty suit,'" Lazare said.
Harris has no choice but to run on Biden's record and while Biden thinks he has been the greatest president since Franklin Roosevelt, the electorate is not so sure, he said.
KILLER INFLATION, FOREVER WARS
Current conditions both within the United States and around the world bode ill for the Democrats' chances; inflation is a killer and there is also the policy of waging wars around the world, Lazare said.
Harris is also trapped in a no-win dilemma over the Israel-Hamas conflict, which has now been continuing for almost 10 months, he said.
"Harris is already under pressure to speak out about Gaza. But [Republican candidate Donald] Trump will pounce on her if she tries to throw peace forces a bone and much of the party base will bolt. My guess is she'll waffle, which will only make things worse," Lazare said.
Harris' clear track record marked her out as a weak candidate likely to lose decisively in November given she has plenty of deficiencies, her political record is full of holes and she's up against a consummate political performer, Lazare added.
LACK OF LEADERSHIP
Before she could even fight an uphill battle against a confident Trump, Harris still had to win her party's nomination in Chicago, University of Pittsburgh Professor of Political Affairs Michael Brenner said.
However, the Democrats' current leadership is of such poor quality they are incapable of rising to the challenge before them to launch an aggressive campaign that personalizes the contest and selects any credible candidate, he said.
"Even as the outside challenger to a mainstream incumbent Democratic administration, Trump had ensured that the 2024 election would be focused on him personally, not at all in line with conventional contests but a referendum on Trump," Brenner said.
In the current election, it is not enough to just oppose Trump; Democrats need a candidate who could present a convincing vision in his or her right, Brenner added.
Billionaire George Soros' son Alex Soros, Wall Street executive Marc Lasry and venture capitalist Reid Hoffman have all already endorsed Harris for president.