Inherent in all of the talk about President Joe Biden ending his candidacy for a second term is the logical assumption that Vice President Kamala Harris is his heir apparent and likely replacement as the Democratic nominee.

Yet, there are substantial doubts among many about Harris' ability to win the presidency, and an alleged years-long grudge held against her by first lady Jill Biden could result in Harris being ousted from her presumptive perch, according to multiple media sources.

Will Joe stay or will he go?

The Hill reported earlier in the week that multiple Democratic insider sources claimed that President Biden would soon decide whether or not to step aside from his re-election bid and hand the reins of the campaign over to VP Harris as his successor nominee.

The sources further indicated that tentative plans were being formulated on a search for a running mate for Harris as well as who would assist her in the transition to a newly revamped campaign with her at the top of the ticket, in the event that Biden acquiesced to the mounting pressure to exit the race.

Yet, even as those insiders seemed to acknowledge that Biden's quest for another term was essentially over regardless of his decision to drop out or stay in the mix, he and those closest to him, including Harris, have remained defiantly insistent that he will not step aside and will continue his run to remain in the White House.

However, that plan has not gone particularly well, as evidenced by an NBC News report on a conference call between Harris and hundreds of "frustrated" donors that was meant to reassure them but had the opposite effect due to her being late to the confab that was reportedly disorganized, "mismanaged," and "rushed" by campaign staffers.

Sources with direct knowledge of the call described it as a "total failure" and "damaging" to the campaign as it reflected "poor planning" that left donors feeling "annoyed," with one even calling the whole thing "ludicrous."

Serious doubts about Harris' electability

Meanwhile, at the same time, Politico published a lengthy report documenting the many causes for concern and doubt among Democrats about VP Harris ascending to the top of the ticket in place of President Biden, and why that outcome ultimately may not occur.

Those reasons include but are not limited to her poor polling against former President Donald Trump and general favorability with the public, her failed 2020 campaign prior to being picked by Biden as his running mate, her reportedly dysfunctional office and dismal performance as VP, and legitimate questions about whether she would be capable of uniting the various blocs and demographic groups within the Democratic Party's base into a winning coalition.

Another potentially serious problem for Harris is the difficulty she has had in garnering support from Biden's tight inner circle, especially first lady Jill Biden, as there reportedly remain hard feelings from the direct attacks Harris launched against her future boss during the 2020 primary debates.

Jill's years-long grudge against Kamala

The Daily Mail reported exclusively about a week earlier that Jill Biden still holds a deep grudge against Kamala Harris for implying that her husband was a racist in league with segregationists during the 2020 primary debates and even strongly advised against her being picked as Biden's running mate.

Now, Jill is said to be the driving force keeping Joe in the race, largely because she "has become consumed by the power and prestige of the presidency and what that means to her," according to one unnamed source, and doesn't want to give it up to anyone, least of all Harris.

One source said that Jill is "absolutely unwavering about Joe staying [in the race] but if he is forced out or opts out, she would be fully opposed to Kamala replacing him," while another source claimed that "Kamala never runs competent organizations. Every office, every campaign, devolves into toxicity. And Jill is keenly protective of Joe's legacy."

All of that may not matter in the end, though, as all of the first lady's perceived leverage and power will be greatly diminished if and when Biden eventually drops out of the race.