Complex sentence: As communist groups, left-wing groups, and anti-war groups were illegal since 1940, they were unable to name a candidate in the election, communists, left-wing politicians and radical anti-military politicians were arrested and even not allowed to run as independents.
Split into simpler sentences: As communist groups, left-wing groups, and anti-war groups were illegal since 1940, they were unable to name a candidate in the election. Communists, left-wing politicians and radical anti-military politicians were arrested and not even allowed to run as independents.