Some members of Combat Communiste were won over to the positions of the International Socialists (IS, forerunner of the SWP) and sought to win other militants to their views before launching an independent group of their own.
They joined the Ligue Communiste Revolutionnaire (LCR) to further that aim and later left to found the Socialisme International group.
SPEB grew somewhat during the radicalisation in France in the late 1990s around the anti-capitalist movement, but was still too small to take full advantage.
It joined ATTAC en masse, but when the latter began to lose the initiative and stall in the aftermath of 9/11, it started to concentrate its efforts on building Agir Contre La Guerre (Act Against the War).
In late January 2004 SPEB, then numbering approximately 50 militants, was permitted to join the LCR as a faction.