Senate Ways and Means chairman Stephen Brewer said Thursday that he will not seek reelection in November, ending a State House career he said began in 1980 when he was a legislative aide. Brewer, a Barre Democrat, lost a bid for the Senate presidency last year when Stanley C. Rosenberg of Amherst said he had sufficient votes. Brewer took the chairmanship of the Senate’s budget-writing committee in 2011 and has long worked on veterans affairs. In a press release, Brewer said he plans to serve out the remainder of his term.Jim O’Sullivan can be reached at James.OSullivan@globe.com. Follow him on Twitter at @JOSreports.