KINSHASA (Reuters) - Tens of thousands of Congolese rallied on Saturday in support of President Joseph Kabila’s preferred successor, two months before an election that could mark the country’s first democratic transition of power.

Kabila selected Emmanuel Ramazani Shadary, a former interior minister, in August to represent his ruling coalition, the FCC, in the Dec. 23 vote, ending years of speculation about whether he would defy the constitution by seeking a third term in office.

Kabila’s decision not to run calmed fears that the violence sparked by his refusal to step down when his mandate expired in 2016 could escalate into another civil war in Democratic Republic of Congo.

FCC supporters waving the flags of its member parties and banners emblazoned with Ramazani’s face packed the bleachers and playing field at the capital Kinshasa’s Tata Raphael Stadium to hear speeches by Ramazani, Prime Minister Bruno Tshibala and others.

“For the elections of December 23, we are going to run a civilized electoral campaign. We are going to run a beautiful campaign, and we are going to win,” Ramazani, wearing a white shirt and white FCC cap, said in brief remarks.

The rally demonstrated the coalition’s ability to mobilize large crowds despite both Kabila’s deep unpopularity after nearly 18 years in power, according to the polls, and Ramazani’s lack of broad name recognition.

A poll in July, before Kabila gave Ramazani his backing, showed opposition leaders were favored by about 70 percent of voters, but the majority enjoys significant financial and institutional advantages.

Several prominent opposition leaders, including former vice president Jean-Pierre Bemba and millionaire businessman Moise Katumbi, were barred by authorities from running in decisions the opposition said were politically motivated.

The opposition has yet to coalesce behind a single candidate despite repeated promises to do so.

There are 21 candidates in the single-round contest, meaning victory could require significantly less than half the vote.

“The FCC is an electoral machine,” said Nicole Fatou, a supporter at the rally from Ramazani’s home province of Maniema in eastern Congo. “We have filled the stadium. There are even more outside. We are going to keep power with Ramazani Shadary.”

The opposition also accuses the government of trying to rig the election, using new electronic voting machines imported from South Korea. The government denies the charge.

On Friday, thousands of opposition supporters marched in Kinshasa to demand that the machines be withdrawn and paper ballots used instead.

Since independence from Belgium in 1960, Congo has experienced coups, civil conflicts in which millions have died, and long periods of authoritarian rule.