The word 'faction' is correct and usable in written English.
You can use it to refer to a small group of people within a larger group, typically having a shared goal or interest. For example, "The faction of members who support the proposal is growing."
And because the book-buying upper-middle class does not trust the entrenched positions of America's ideologues, they are looking for fresh thinking – which a foreigner like Piketty, whose positions are not those of any large American political faction, provides.
As leader of the far-left faction within Tsipras's Syriza party, and the cabinet's effective number three, Lafazanis has considerable say in government policy.
It contains a bewildering number of intellectual currents – from the moderate "democratic socialism" faction to the more libertarian "emancipatory left" to Cuba Sí to the hardline Communist Platform; for some the prime goal is "resistance", for others it's "governing".
Last week the new Nationalist party was formed, combining football hooligans, ultranationalists and skinheads, while another faction announced the creation of vigilante groups.
The leader of Friday prayers, Ayatollah Imami Kashani, who often reflects the political mood among the conservative faction of the Islamic republic, said: "The Lausanne declaration was a success.
He had no substantial faction to back him.
Hope of ascent up the parliamentary pecking order – or fear of a punitive pecking by a rival faction – often comes before appraisal of the arguments.
Unfortunately, a vocal faction within the Republican party believes it is their responsibility to define narrowly the party's political agenda, at least where it concerns the freedom to marry for gay men and women.
Among those are six victims of the IRA and one INLA member killed and buried in secret in France by rival members of the republican faction.
Bowen, a member of the right faction of the New South Wales branch of the Labor party, presides over a diverse and multicultural seat in Sydney's west.
"We are a resistance faction that have been fighting for 11 years.
