With few caveats, House Democratic leaders said they could pass a downsized plan that would raise about $170 million in net revenue annually, a drop from the earlier financial projections of $187 million for a broader plan that included medium-sized trucks. By exempting all but the largest commercial trucks, the legislators and Gov. Ned Lamont are willing to forgo revenue in favor of a political benefit: Countless local small businesses that use box trucks and smaller vehicles now would be unaffected by tolls, presumably taking away potential supporters of the no-tolls movement. The administration says half or more of the revenue would come from out-of-state trucks, according to modeling done by the state Department of Transportation.