The top six leaders from the ruling and main opposition parties will hold monthly meetings starting this week in an effort to boost their cooperation on last year\'s campaign pledges, the parties\' chief policymakers said Monday.The chairman, floor leader and chief policymaker of the ruling Saenuri Party will meet with their counterparts from the main opposition Democratic United Party (DUP) each month to discuss ways to fulfill the campaign promises they both made ahead of last December\'s presidential election, Saenuri chief policymaker Na Seong-lin and his DUP counterpart Byun Jae-il said during a joint press briefing.