Accordingly, I’ve supported equally those radical activists who have entered these parties to try and encourage this development in opposition to the neoliberal direction of their leaders. This includes participation in the Democratic Party in the US, whose base in the unions and allied social movements, program, leadership, rivalry with the dominant right of centre party, and behaviour in office is virtually identical with that of Labour in Britain and the Socialist parties in Europe and elsewhere.
This view has been criticized by many of my friends on the Marxist left, who consider so-called “entryism” into these left-centre parties as a graveyard for radical politics. In some cases, they continue to distinguish between the “bourgeois” Democratic Party and the flawed “workers’ parties” in England and on the continent. But in the main they denounce these parties and run or support their own fringe candidates against them.
The movements behind the Corbyn and Sanders candidacies in the Labour and Democratic parties appears to confirm that the initial stages of any radicalization from below will first appear most strongly in the major left-centre parties. In times of distress, people understandably turn first for relief to what is nearest at hand, to the parties they know and support, and particularly to those party figures who speak directly to their needs.
As Richard Seymour observes in the article linked to below: “It is often assumed by Marxists that capitalist crises are polarizing events. That is not always straightforwardly true…the dominant reflex (is) to seek a reassuring center ground, to trust in a middle-of-the-road figure who would at least be relatively honest and fair in the handling of the crisis.”
Ultimately, whether these movements flare out and are turned back into the party mainstream, as has typically happened, or whether they develop beyond the confines of the established parties and electoral system will essentially depend on whether capitalism is able to again recover from the latest of its recurrent crises. Less important are the intensions and leadership qualities of Corbyn and Sanders.
https://www.jacobinmag.com/2015/09/jeremy-corbyn-labour-benn-kendall-blair-leadership/