Sen. Scott Brown (R-Mass.) is taking sides in the race to succeed retiring Rep. Bill Delahunt (D-Mass.), endorsing state Rep. Jeff Perry in the GOP primary over former state Treasurer Joe Malone.

In a video, Brown calls Perry “a longtime personal friend” and “someone who will stand alongside me to bring an independent voice to the Commonwealth.”

Perry and Brown, a former state Senator, served together as a small coterie of Republicans in the Massachusetts Legislature for much of the past decade.

Not only is Brown about the most high-profile endorsement a Republican can get in Massachusetts (or nationally, for that matter), but he proved to have particularly strong pull in Delahunt’s 10th district, which was one of his best-performing districts in the Senate special election in January.

Perry could use some of Brown’s star power, given that he’s starting out with much lower name identification than Malone, who has run for and held statewide office in the past.

Another popular GOP figure in the Commonwealth, former Gov. Bill Weld (R) endorsed Malone on Tuesday. Weld and Malone served side by side in state government in the 1990s.

Two top-tier Democrats are also in the open-seat race — state Sen. Robert O’Leary and District Attorney William Keating.