Nick Clegg, Tim Farron, Vince Cable...Gina Miller? That's the line of succession senior Lib Dems are dreaming of. The party's leadership is planning to amend its constitution to allow any party member to run for the top job, this morning's Daily Mirror reported without a denial from Team Cable.

Miller, the anti-Brexit campaigner whose successful lawsuit against the government gave MPs a vote on triggering Article 50, is the contender for whom the new rules are said to be designed.

The story here is one of a party desperately seeking a purpose. That the conversation around the Lib Dem leadership has shifted in the space of a year from Cable, 75, pledging to fight the next election and likening himself to Gladstone, who became prime minister for the last time aged 81, to talk of plots to depose him and outlandish succession planning is a mark of just how poisonous its internal dynamics have become, despite some signs of electoral recovery.

One party source tells me that Cable has indicated privately that he is fed up and will step down within a year, which is flatly denied by his team. But the leak of the plans to shake up leadership elections – and the hostile briefing that accompanied it – underlines the extent to which the party is preoccupied with discussion of his performance and future.

Having lost his second chief of staff in a year, Cable is currently recruiting for a replacement, a process which is already stirring disquiet internally. His absence from votes on Brexit legislation last week provoked uproar. Talk of an imminent coup abounds. Some are agitating for Layla Moran, the star of the 2017 Lib Dem intake, to replace Cable, and its deputy leader Jo Swinson is favoured by those who believe Moran is too inexperienced.

The plan to allow an outsider like Miller (who, despite not being a member, will be one of the opening speakers at September's Lib Dem conference) to run for the leadership has naturally been spun by Cable's internal rivals as a way of thwarting any challenge from Westminster, though his allies told the Mirror that it would "actually open him up to far more challenges".

But news of the proposed changes to the leadership rules, which I'm told have the curious working title of "Project Ozark", was nonetheless met with bemusement by party staff and those who were aware before the news broke are divided as to whether it's a good idea (presumably the name is inspired by the Netflix crime drama about a money-laundering financial planner indebted to a Mexican drug cartel, which doesn't seem directly analogous to the party's struggle to win back St Albans.)

There is also a degree of understandable consternation among veterans of the parliamentary party and internal operation. One such senior source describes it as a "bad and dangerous idea" born of frustration with a cohort of 12 MPs diminished in number and standing ("crackpot" is the less charitable description another offered to the Mirror).

"In the era of social media it has been shown by Momentum how it is relatively easy for a pressure group to gain control of a political party and change it irrevocably," my source said. "Long-term values must be more important for leaders than what might be single issues or short-term populist causes which could be driven by media and social media to determine the leadership whilst excluding the filter of at least being an MP. Non MPs seeking the leadership should show that they can win a constituency first."

Complaints like these speak to the bitter debate among Lib Dems as to how they should answer the existential question facing them: what exactly are is their party for? Which route does it take out of the electoral wilderness? Should it surrender to a reverse takeover and let a new anti-Brexit centrist movement subsume it? Should it ditch its continuity remain strategy and reclaim a sense of political purpose beyond Brexit? As yet, there is no settled consensus as to what the answer is.

The party also has a generational divide to contend with. The flood of new members that have signed up since the EU referendum, some older hands complain, are primarily motivated by Europe and aren't really in tune with party policy on anything else. With March 2019 rapidly approaching, the Lib Dems face a stark choice: bet the house on anti-Brexit sentiment with a new leader like Miller and morph into a very different party, or chart a different political path that stays true to their old identity.

Bluntly, neither option promises much: having come second in only 37 seats in 2017, the party's path to relevance at Westminster and in the country at large is much narrower than previously. Almost all agree that change is required. But there is no such consensus on just what the change should, or will, be. Today's backlash illustrates that the process of reaching one will be messy – and Cable could well be its main casualty.