Of the $414,880 Belmont residents have spent on campaigns for statewide offices and ballot questions since the start of the year, $117,266—about 30%— has gone toward the campaign to re-elect Belmont resident state Sen. William Brownsberger. A majority of those dollars, however, were donated in the days and months leading up to the primary race earlier this fall—a race Brownsberger won by a razor-thin margin against challenger Daniel Lander, a former senior aide to Boston Mayor Michelle Wu. The race…