Brochin becomes the second candidate in the June 26 Democratic primary, joining former state Del. Johnny Olszewski Jr. of Dundalk. County Councilwoman Vicki Almond of Reisterstown is expected to launch her campaign Nov. 1.
All are vying for the county executive seat that's open because current County Executive Kevin Kamenetz, a Democrat, is term-limited. Kamenetz is now running for governor.
Brochin has spent four terms representing Towson and parts of northern Baltimore County in the state Senate. But he's never been a favorite of leaders in his party, and he isn't involved in the county's decisions on development — other than fighting some of them along with his constituents.
"More and more, part of my daily work as a senator has been on stopping overdevelopment, which isn't really supposed to be a part of a senator's job," said Brochin, 53, who lives in Cockeysville.
Brochin says that as county executive, he would make land preservation and smart redevelopment priorities. He also promises to push for ethics reform, more treatment options for heroin addicts, additional college- and career-prep programs for public school students, and new strategies to help the homeless.
"This county could run on autopilot; it could. But it shouldn't," Brochin said. "We need vision, and we need to be better than we are, and we need to strive for it."
John Dedie, professor and coordinator of the political science program at the Community College of Baltimore County, said he expects the Democratic primary to be "very competitive."
Brochin, he said, will benefit from his reputation as an independent-thinking politician and draws support from the central and northern parts of the county. It could be a weakness, however, not to have the support of party leaders.
Olszewski, meanwhile, has positioned himself to the political left, though his base of support in the eastern part of the county is becoming increasingly conservative.
Brochin said he's looking forward to forums and opportunities to make his pitch to voters. Brochin and Olszewski are scheduled to appear before several Democratic clubs in early November, and an event at the community college is in the works.
"If you ask me a question, you're going to get an answer, and it's going to be a straightforward answer," Brochin said. "You're not always going to like it, but you now where it comes from and you know what I'm going to do."
Olszewski, in an interview, welcomed Brochin into the race. But Olszewski argues he's the best Democrat for the job.
"I'm the candidate who best reflects our shared Democratic values, and I look forward to the discussion over the next 35 weeks," he said.
Olszewski's campaign later sent out a critique of Brochin's voting record, saying the senator has opposed "progressive initiatives."
Brochin acknowledges that he's not always in lockstep with the Democratic Party, which he says is because he focuses on policy more than politics.
"Even though I'm a Democrat, I've never played party," he said. "I've always done public policy over party. I've always done ideas over ideology."
Brochin works as an insurance broker and first ran for office himself in 2002, winning a seat in the state Senate, after working for others. He cut his teeth while in graduate school with an internship as a bill analyst for Senate President Thomas V. Mike Miller and ran American Joe Miedusiewski's unsuccessful campaign for governor in 1994.
Brochin says he's "kind of a nerd" about public policy and hopes to use his expertise to help his home county.
"I've lived in this county my whole life, and somebody in this county needs to try to protect it," he said. "And I think that if we let the developers and the council people have their way, we are going to hurt the quality of life in Baltimore County."
Experience: Four terms as a state senator; chairman of Baltimore County Senate delegation; insurance broker.