Kamenetz joins several Democrats who already are vying for a chance to unseat popular Republican Gov. Larry Hogan in 2018: Prince George's County Executive Rushern Baker, former NAACP leader Ben Jealous, state Sen. Richard Madaleno, technology entrepreneur and author Alec Ross, lawyer Jim Shea and Krish Vignarajah, a former policy director for first lady Michelle Obama.
Maya Rockeymoore Cummings, a policy consultant who is married to Rep. Elijah E. Cummings, has said she is considering a run.
Kamenetz, who has long been laying the groundwork for a gubernatorial campaign, has clashed frequently with Hogan. The two have publicly disagreed over the sale of a county government center in Dundalk to a developer, the pace of installing air conditioning in Baltimore County public schools, and whether to use pesticides to combat midges on the Back River, among other issues.
Kamenetz has made public appearances throughout the state, sometimes in his role as president of the Maryland Association of Counties. He has visited Democratic picnics and breakfast club meetings, appeared at fundraisers for other candidates and sponsored an event for Western Maryland Democrats.
Kamenetz says he's the best choice for Marylanders who want a governor who will stand up to President Donald Trump's "harmful policies and shameful rhetoric."
"I think people are frustrated that we aren't doing big things any more in Maryland," he said. "They're scared by what's taking place in Washington and they're frustrated by the lack of progress in Maryland."
As an example, Kamenetz pointed to Trump's immigration policies, including a travel ban affecting people from Muslim-majority countries and promises to build a wall on the border with Mexico. Kamenetz issued an executive order emphasizing that Baltimore County police officers and government workers would not ask the people they stop about their immigration status or enforce immigration law.
As governor, Kamenetz said, he would employ some of the strategies he's used as county executive. He said he streamlined government agencies while increasing the use of technology to help counter declining tax revenues following the recession.
Kamenetz has used county government resources to help spur development in some areas, including building a library and community college campus at the previously stalled Owings Mills Metro Centre and drawing up a blueprint for the old Sparrows Point steel mill that's influenced the Tradepoint Atlantic project there.
Kamenetz also says he's worked to improve schools through his $1.3 billion "schools for the future" campaign — the county, home to some of the state's oldest school buildings, is constructing new ones and renovating and installing air conditioning in others.
And he touts recruiting more diverse police trainees and outfitting patrol officers with body cameras.
"I'm a guy who sweats the details, does the hard work and gets real results," he said. "I'm going to be one of the hardest-working governors ever."
But first, Kamenetz needs to be a hard-working candidate if he wants to win the Democratic nomination, according to political observers. Kamenetz is the seventh Democrat to get into the gubernatorial race, making it challenging for voters to distinguish among them.
The primary is June 26. The general election is Nov. 6, 2018.
"He's got to get that name out there," said Todd Eberly, an associate professor of political science at St. Mary's College of Maryland. "The more people that get into this race, the threshold for winning just gets lower and lower. In that respect, it becomes wide open."
Eberly said Kamenetz has some advantages. He has significant experience in governing, and has done so in a county that's politically mixed.
The Baltimore County electorate is 56 percent Democratic, 26 percent Republican and 16 percent unaffiliated. The Democrat Kamenetz won a second term as county executive in 2014 even as 59 percent of county voters went for the Republican Hogan for governor.
Mileah Kromer is director of the Sarah T. Hughes Field Politics Center at Goucher College.
"Kevin Kamenetz is able to say: 'I've been able to govern over a politically divided Baltimore County,'" she said. "It's much harder when half of your residents are [from the other party] to find solutions for good governance."
At the same time, Kromer expects Kamenetz could appeal to Democratic voters by playing up the fact that he's been "a thorn in the side" of the governor.
"Kamenetz does have an open track record of pushing back against the Hogan administration," Kromer said.
Kamenetz began his political career as a teenager, when he was president of the politics club at the Gilman School.
After graduating from the Johns Hopkins University in 1979, he worked on then-Baltimore Mayor William Donald Schaefer's re-election campaign. Kamenetz said he embraced Schaefer's "do it now!" model of governing.
Despite more than 20 years in elected office — four terms on the Baltimore County Council and two as county executive — Kamenetz said he still thinks of himself as a lawyer first. He graduated from the University of Baltimore School of Law and was an assistant state's attorney early in his career. He later switched to private practice. He gave up his practice after he was elected county executive in 2010.
"I view politics as a passion," he said.
Residence: Owings Mills
Education: University of Baltimore School of Law, the Johns Hopkins University; the Gilman School
Experience: Baltimore County executive; president, Maryland Association of Counties; four terms on the Baltimore County Council; private law practice; assistant state's attorney