WellPoint Inc., UnitedHealth Group Inc.and three other health insurers, criticized by Democrats during the overhaul debate, are seeking to influence how the new law will be implemented, and possibly change it, by campaigning for supportive congressional candidates. Senior government-relations staff from UnitedHealth, WellPoint, Humana Inc., Aetna Inc. and Cigna Corp. have been meeting for at least two months to discuss the plan, which may include creation of a $20 million war chest, said two people familiar with the matter. The group also is debating whether Karen Ignagni should remain head of the trade group America’s Health Insurance Plans, said a third person familiar with the discussions. All declined to be named, as the talks are private. The strategy sessions mark the first major public split from within the trade group, known as AHIP, over how to address the overhaul. The five largest publicly traded insurers may be unhappy with how the group represented them in the debate, said Paul Keckley, of the Deloitte Center for Health Solutions.