In recent weeks, the talks have been led by Sens. Ben Cardin (D-Md.) and Roger Wicker (R-Miss.), according to four people familiar with the matter, who spoke on the condition of anonymity to describe their work, which is ongoing. The duo in mid-December cobbled together the outlines of a roughly $68 billion proposal, two of the people said, which could include a mix of new spending and a repurposing of some unused cash authorized under previous packages.