But such a split would greatly affect Wallonia, which depends largely on Flemish funds. Polls ahead of the vote gave the country's socialists at least 30 per cent of the vote there.
However, even if De Wever emerges victorious, he will not be able to begin devolving powers to the regions immediately.
The electoral system - effectively two elections with separate parties seeking votes from French-speakers and the majority Dutch-speakers - means at least four parties will be needed to form a governing coalition.
Bilingual voting dispute
Voting is obligatory for the 150 parliamentary seats in the country of 10.5 million people, 60 per cent Flemish, where no political party operates nationally.
The polling stations are to close at 1300GMT with the first results expected within three hours.
Sunday's elections were called one year early, after the five-party coalition of Yves Leterme, the prime minister, fell apart on April 26 in a dispute over a bilingual voting district.
That spat has pushed the New Flemish Alliance into the top position in the polls.
"We did a study of 10,000 people and found 84 per cent want the country reformed, but not broken apart."
However some in Belgium say they favour more self-rule for the country's different language regions, but no division.
"We did a study of 10,000 people and found 84 per cent want the country reformed, but not broken apart,'' the Associated Press news agency quoted Marianne Thyssen, a Dutch-speaking Christian Democrat, as saying.
Strict language rules determine which language is used in Belgium on everything from mortgages and traffic signs to election ballots and divorce papers.
In 2003, the country's constitutional court ruled that the bilingual voting district comprising the capital, Brussels, and 35 Flemish towns bordering it, was illegal because it violated the separation of Dutch- and French-language regions.
The high court ruled it illegal as only Dutch is the official language in Flanders.