DAKAR (Reuters) - Niger’s ruling party candidate Mohamed Bazoum was slightly ahead of his challenger on Monday as vote-counting continued in the West African nation’s presidential run-off, electoral commission data from nearly a quarter of constituencies showed. With 62 out of a total 266 constituencies counted, provisional results showed former interior minister Bazoum ahead of his challenger, former president Mahamane Ousmane, with 51.49% of the vote, a lead that had narrowed from earlier in the day. The run-off vote, meant to usher in Niger’s first transition of power from one democratically elected leader to another, was held on Sunday after neither candidate secured a majority in the first round in December. Voting was marred by the death of seven election workers after their vehicle hit a landmine on Sunday, underscoring a fraught security climate as a result of Islamist insurgencies. One of the world’s poorest nations, Niger has also struggled with drought, floods, coronavirus and weak prices for its main export, uranium.