A divided Clark County Commission rejected a collective bargaining agreement covering 85 percent of University Medical Center's workforce today over concerns about the inclusion of longevity pay for new hires, a benefit that is paid out to long-term employees. The issue: Clark County commissioners considered a new three-year collective bargaining agreement for nurses and other nonmanagement staff at University Medical Center. The vote: A motion to approve the contract failed 3 to 4, with Commissioners Steve Sisolak, Larry Brown, Susan Brager and Mary Beth Scow in opposition.