Del. Jon S. Cardin (D-Baltimore County) formally kicked off his campaign for Maryland attorney general on Monday morning with a Web video in which he pledges to protect families “from the next-generation challenges they face.”

“Families are facing new and complex challenges in today’s rapidly changing world, and I believe Maryland’s next attorney general must be aggressive enough and savvy enough to stay one step ahead of anyone seeking to harm our families, whether on our streets or in cyberspace,” said Cardin, a member of the House of Delegates since 2003 who has been gearing up to run for statewide office for months.

With his announcement, Cardin joins what is expected to be a crowded race next year to succeed Attorney General Douglas F. Gansler (D), who plans to announce his bid for governor in September.

Others eyeing the June Democratic primary include Sen. Brian E. Frosh (D-Montgomery), Del. C. William Frick (D-Montgomery) and Del. Aisha N. Braveboy (D-Prince George’s).

In his video, Cardin is literally shown running, early morning exercise that he says clears his head and gets him ready for the day. The video also includes testimonials from several people — including Sen. Benjamin L. Cardin (D-Md.), the delegate’s uncle — and it recounts bills Cardin that has worked on in the General Assembly.

He highlights his work as chairman of an election law subcommittee and his sponsorship of a bill last year that made “cyberbullying” a crime.

“Twenty years ago, we could have never envisioned that this new thing called the Internet would become the preferred vehicle for predators and bullies to go after our children – but that’s the world we live in,” Cardin said, calling the legislation an example of the “forward-thinking ideas I look forward to bringing to the attorney general’s office.”