Ukrainian self-defense fighters who clashed with armed pro-Russian separatists on Friday are at the forefront of Kiev’s efforts to prevent the country from splitting.

Co-funded by Ihor Kolomoisky, one of Ukraine’s richest men, they play a more assertive role than the unarmed miners and metalworkers working for another oligarch, Rinat Akhmetov, who more recently spoke against the rebels.

At least two people were killed in Friday’s firefight involving the pro-Ukrainian “Donbass Battalion” allied to Kolomoisky. The violence took place two days before a presidential election that the separatists have vowed to disrupt.

Kolomoisky, appointed governor of the eastern region of Dnipropetrovsk in March, has spent tens of millions of dollars, an aide said, to prevent his territory from falling, like the regions of Donetsk and Luhansk to the east, into separatist hands and being proclaimed autonomous “people’s republics.”

The 51-year-old, who is among Ukraine’s five richest men, has put a $10,000 bounty on the head of any Russian “saboteur” and has bought up weapons from people to help pacify the region.

With Kiev’s blessing, he is now seeking to expand his influence with an offensive to win back ground in the two neighboring regions, where separatists have seized strategic public buildings and called for union with Russia.

The forces allied to him are already patrolling four western districts of the Donetsk region where he helped install pro-Ukrainian locals in governing roles, and three more districts are expected to follow, according to his aides.

“We are doing all this in agreement with the central government. We coordinate and cooperate with Kiev. They accept that we are influential as a consolidating factor in the east,” Kolomoisky’s deputy Borys Filatov said in an interview. “Our goal is to knit the country back together,” said the 42-year-old lawyer and real-estate businessman after a meeting with voters in the Dnipropetrovsk region, whose 3.3 million people make up 7 percent of Ukraine’s population.

Ukraine’s long-running political crisis escalated sharply in February when mass street protests toppled Moscow-backed President Viktor Yanukovych and he fled to Russia. Moscow then grabbed Ukraine’s Crimea region after declaring Kiev’s interim authorities illegitimate and hostile to speakers of Russian.

It remains unclear to what extent voters in the eastern regions will be able to take part in Sunday’s election.

In a sign of the trust that Kiev now has in Kolomoisky and his political clout in Ukraine’s Russian-speaking southeast, his ally Igor Palitsa was named head of the Odessa region and tasked with easing tensions after dozens were killed in clashes in the port city of Odessa earlier this month.

Igor Bereza, a commander in Kolomoisky’s National Defense Force, said the force now has nearly 15,000 people, including some 2,000 combat-ready troops organized in four battalions.

The battalions still formally take orders from Ukraine’s army and law enforcement bodies, but their members earn about twice as much and are better equipped, he said.

Ukraine’s political crisis has shone a harsh spotlight on the parlous state of the ex-Soviet republic’s military forces.

“The problem is that there was never such a thing, really, as the Ukrainian Army. Our top generals — most senior officers — still do not see Ukraine as a truly separate and sovereign country,” said Bereza. The fall of the Soviet Union in 1991 gave Ukraine independence.

In Dnipropetrovsk, where Ukrainian yellow-and-blue national flags are seen all around the city of 1 million people, there is much less tension than in Donetsk, but Bereza’s men feel the deadly gravity of Ukraine’s predicament.

“I thought the war was long over for me. It’s still hard to believe we are fighting on our own soil,” said Oleksandr Rybich, who served in Afghanistan in the Soviet Army in the 1980s and now mans the Bratske checkpoint outside Dnipropetrovsk.

Many in Dnipropetrovsk compare Kolomoisky favorably with Ukraine’s richest man, Akhmetov, who is based in Donetsk, where he owns steel mills and coal mines. Akhmetov kept a diplomatic silence as separatists took control of the city.

Kolomoisky, who is a senior figure within Ukraine’s Jewish community, co-owns the country’s largest lender, Privatbank.

Belatedly, Akhmetov condemned the separatists last week and ordered his workers to join daily protests to register their opposition to the separatists who have seized public buildings and other key sites in several cities and towns.

“We were just lucky to get a better oligarch,” said Yevgeny Khapatko, a 24-year-old self-defense member at the Bratske spot. “Much of Kolomoisky’s business is here; he is trying to protect that. Akhmetov has stronger ties with Russia. In the end, he has overplayed his hand.”

In Donetsk, where many accept Moscow’s line that Kiev is now ruled by dangerous nationalists bent on making Russian speakers second-class citizens, Kolomoisky is viewed very differently.

“Before all these events, I thought Kolomoisky was a normal businessman. Now Kolomoisky has taken a pro-Nazi, pro-fascist stance that I cannot understand,” said Nikolai Zagoruyko, head of the Party of the Regions faction in Donetsk’s regional parliament. “He is financing mercenaries. . . . He and Kiev will tear the country apart,” added Zagoruyko, whose party was once led by Yanukovych.

“Akhmetov and other businessmen in the Donetsk region sought to distance themselves from all this, to prevent the conflict and the violence,” he said.