A mainstream Flemish party that is expected to do well is invoking the concept of irreconcilable differences to seek a separation and, in time, take the country's Dutch-speaking Flanders region into the European Union as a separate nation.
This is a nightmare scenario for poorer Wallonia, Belgium's Francophone south, which greatly depends on Flemish funds.
Early elections were called after premier Yves Leterme's five-party coalition fell apart on 26 April in a dispute over a bilingual voting district.
That issue has pushed the New Flemish Alliance – a tiny, centrist party only a few years ago – into pole position: it is forecast to win a quarter of the vote in Flanders.
Its leader, and perhaps Belgium's next premier, Bart de Wever, 39, wants an orderly break-up of Belgium by shifting the national government's last remaining powers, notably justice, health and social security, to Flanders and Wallonia.
Such a move would complete 30 years of ever greater self-rule for the two Belgian regions.
The new Flemish alliance wants Flanders to join the EU. There are no comparable separatist sentiments in Wallonia.
Finance minister Didier Reynders, a Francophone Liberal, says the question facing Belgians is: "Do we still want to live together?"
In Belgium just about everything, from political parties to broadcasters to boy scouts and voting ballots, already comes in Flemish and Walloon versions.