To fight from within or to go it alone outside
This, in essence, is what defines the differing responses by Tom Watson and Ian Austin to the turmoil within the Labour party.
The Dudley North MP Ian Austin is opting to resign from it and sit as a lone Independent, unattached to The Independent Group (TIG).
Unlike the TIG members, he is a Leaver while they are all arch-Remainers.
By contrast Labour's deputy leader Tom Watson, MP for nearby West Bromwich East, supported remain and sees his job as "holding the party together".
So he recommends a new grouping within the party specifically for those who belong to the social democratic tradition rather than that of the undiluted Left represented by Jeremy Corbyn and his shadow chancellor John McDonnell.
But there is one important respect in which both MPs have much in common.
They are both responding to the same catalyst: the furore over anti-Semitism in the party.
Crisis for Labour's "soul"
Appearing on the Andrew Marr Show (BBC One, Sunday 24 February 2019) Mr Watson issued a defiant challenge to his leader: to take "a personal lead" over what he called "a crisis for the soul of the party".
He also criticised the language used by the shadow foreign secretary, Emily Thornberry, who says the nine MPs who have resigned from the party have "betrayed" their constituents and would be "crushed" if by-elections were held.
But Mr Watson warns "it's incumbent on all of us to dial-down the rhetoric".
A Labour spokesman says the party "takes all complaints of anti-Semitism extremely seriously. We are committed to challenging and campaigning against it in all its forms. All complaints of anti-Semitism are investigated in line with our rules and procedures and any appropriate disciplinary action is taken".
Mr Corbyn has often repeated his assertion that it does not tolerate racism of any kind.
But his critics in the party accuse him of failing to match his words with deeds: Mr Watson says he has sent 50 complaints of anti-Semitism to the leader's office over the past week alone.
While Mr Watson is fighting from within "to eradicate anti-Jewish racism in all its forms", his Black Country neighbour is so ashamed of the party he joined as a teenager more than 35 years ago that he now feels he has no option but to take what he says is his "most difficult decision ever".
His own personal story goes back even further, to his formative experiences with his Jewish adoptive parents.
"I grew up listening to my dad, who was a refugee from the Holocaust, teaching me about the evils of hatred and prejudice", he says.
"One of the main reasons I joined the Labour party here in Dudley was to fight racism and I could never have believed I would be leaving the Labour party because of racism too."
The ninth MP to leave the party within the space of one week, he blames Jeremy Corbyn for "creating a culture of extremism and intolerance" and for turning the party into "a narrow sect".
But Jeremy Corbyn hits back by reminding him that they were both elected on the same "social justice platform" in 2017 when Mr Austin retained his seat by the narrowest of margins: just 22 votes.
Mr Corbyn also denies claims that bullying is rife in his party and says "bad behaviour" has been dealt with.
A Labour spokesman suggests Mr Austin should stand down and call a by-election, a prospect for which Mr Austin, not surprisingly, shows little enthusiasm.
For both men, much will depend on how this epic drama plays out over the months and even years ahead.
It all has the makings of a political suspense thriller.
If I were the screenwriter, I might yet be tempted to leave the way open for Tom Watson eventually to leave the Labour party.
And for Ian Austin to rejoin it.