Consultants told Business Insider that finding a "sponsor" is the best way to get ahead at top firms.Jennifer A Smith/Getty ImagesConsultants told BI that finding a "sponsor" is the key to career advancement at top firms.Sponsors offer seniority and influence to help employees succeed.Consultants say mentorship is insufficient and that sponsors are key for promotions.Climbing the ranks at a top-tier consulting firm is often harder than landing the job itself.Several current and former consultants told Business Insider that having the right sponsor — an executive who champions their success — is crucial early on.McKinsey & Company defines sponsors as high-ranking employees who "offer seniority, power, and influence to help you meet your goals." They differ from formally assigned mentors, who assist with annual reviews, guidance, and emotional support.