A bipartisan group of lawmakers unveiled a detailed COVID-19 aid proposal on Monday in hopes it would serve as a model for its battling leaders to follow as they try to negotiate a final agreement on a new round of virus relief. The dozen or so lawmakers unveiled two bills. One is a $748 billion aid package containing money for struggling businesses, the unemployed, schools, and for vaccine distribution. The other bill proposes a $160 billion aid package for state and local governments that’s favored by Democrats and GOP-sought provisions shielding businesses from COVID-related lawsuits.