Bruno Tshibala, 61, had been a key player in the opposition coalition known as the Rassemblement that signed a political agreement with the ruling party in December.
Not long after that accord was reached, however, Congo's top opposition politician, Etienne Tshisekedi, died of a pulmonary embolism while seeking medical treatment in Belgium.
Thisekedi's son Felix emerged as a successor, but Tshibala contested his legitimacy as the new UDPS party head and was ultimately excluded from the party.
Under the December agreement, the opposition coalition was to pick a prime minister, but internal divisions complicated efforts to choose a candidate. Earlier this week Kabila said he would announce his own choice if no consensus could be reached.
Kabila came to power after the 2001 assassination of his father, and the opposition reacted strongly late last year when the next presidential election wasn't held. Dozens were killed in violent demonstrations around the country, according to human rights groups.
The Catholic church intervened and held political talks with all the parties in an attempt to avoid more deadly clashes. The agreement reached in December has been slow to implement but calls for Kabila to step down after the next vote, expected before the end of this year.
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