Doug Gansler met with the press after his Tuesday rally, where he announced that he's running for governor. (Michael S. Williamson/The Washington Post)

Maryland Attorney General Douglas F. Gansler formally joined a fiercely competitive Democratic primary for governor Tuesday, casting himself as the outsider in the race and pledging to put the interests of middle-class Marylanders first.

Gansler, a Yale-educated former Montgomery County state’s attorney, announced his 2014 bid outside the courthouse in Rockville, which he said symbolized his commitment to fairness and “standing up for the hard-
working people of Maryland.”

“I’m not your candidate if you want the status quo,” Gansler told about 250 supporters as he embarked on a 17-stop tour that will stretch over the coming week. “I have never just gone along to get along.”

Gansler, 50, joins a primary race with two Democrats who have already announced their intentions: Lt. Gov. Anthony G. Brown and Del. Heather R. Mizeur (Montgomery).

Brown announced his candidacy in May and named Howard County Executive Ken Ulman as his running mate in June. Ever since, he has been collecting dozens of endorsements from fellow Democrats, including Gov. Martin O’Malley, who is term-limited, and Sen. Barbara A. Mikulski (Md.), who rarely takes sides in primaries.

Gansler, who began the year with a sizable fundraising advantage, calculated that he would be better served by waiting to officially announce until the fall, when more people were paying attention to the race. The announcement came exactly nine months before Democratic voters are scheduled to choose a nominee in the June primary.

“The entrenched political establishment, the machine, the special interest groups, the Annapolis lobbyists would like to make that choice for you,” said Gansler, who was framed by a pair of oversized red campaign signs. “But it is the people who actually decide who will be the next governor.”

Although he had steadfastly avoided calling himself a candidate before Tuesday, Gansler has been moving around the state for months, holding a series of events in which he has floated policy ideas he would pursue as governor.

In his “Building Our Best Maryland” forums, Gansler has put forward steps to bolster manufacturing, make government more transparent, reduce domestic violence, help seniors, ease the transition of former prisoners back into society and turn chicken waste into an ­alternate-energy source.

He emphasized his commitment to such proposals Tuesday, and he made several promises in his speech, including reducing what he said is the second-largest minority-achievement gap in the country in public schools. Gansler called that statistic “our biggest moral stain.”

“We will take this on. We will get this done,” Gansler said.

He repeated a call to raise the minimum wage in Maryland from $7.25 to $10 an hour, saying if lawmakers did not act in the next legislative session, it would be his first order of business upon taking office in Annapolis in January 2015.

More broadly, Gansler said job creation would be his “number one priority” as governor.

“Hard-working people feel nickel-and-dimed, and the entrepreneurs we need are not building here in Maryland,” Gansler said.

In recent months, Gansler has not shied away from criticizing the O’Malley administration, of which Brown is a prominent member.

On Tuesday, Gansler again knocked O’Malley for a series of tax increases during his tenure and argued that the state is not competitive with Virginia in attracting businesses.

Gansler has proposed cutting the state’s corporate income tax from 8.25 percent to 6 percent to match that of the commonwealth.

As state’s attorney in Montgomery, Gansler won statewide and national attention by grabbing hold of such high-profile cases as Mike Tyson’s road-rage attack in Gaithersburg in 1998 and the Washington area sniper shootings in 2002. As he runs for governor, he has also talked a good deal about his efforts to help victims of domestic violence during his tenure.

Gansler was criticized while in Montgomery for his frequent appearances in the news media, and he was known to lash out at judges with whose sentences he disagreed.

He made no apologies for that Tuesday, saying: “I’m not worried about what conventional wisdom is. I’m not willing to accept the way things are to play it safe.”

With the retirement of long-serving Maryland attorney general J. Joseph Curran (D), Gansler ran successfully for statewide office in 2006 and unopposed for reelection in 2010.

As attorney general, Gansler has conducted environmental audits of the tributaries that feed the Chesapeake Bay to identify polluters. He has also focused on consumer protection and worked with other attorneys general on issues that include combating the marketing of tobacco products and alcoholic energy drinks to teens.

And in 2009, he successfully argued a case before the U.S. Supreme Court in which the justices unanimously ruled that police may reopen questioning of a suspect who has asked for counsel if there has been a 14-day or more break in Miranda custody.

Gansler’s tenure as attorney general has generally been quieter than his time in Montgomery, although he has continued to speak his mind and demonstrated an ability to make headlines.

In 2010, he issued an opinion that Maryland should recognize gay nuptials performed in other states and that state agencies should immediately begin affording same-sex married couples the same rights that heterosexuals enjoy.

That came two years after Gansler, in 2008, became the first statewide elected official in Maryland to endorse same-sex marriage, which state lawmakers legalized in 2012.

Sen. Richard S. Madaleno Jr. (D-Montgomery), one of three speakers who introduced Gansler on Tuesday, praised the attorney general for his words and deeds on the issue.

“He put his career on the line,” said Madaleno, who is gay.

Gansler’s tour was scheduled to continue Tuesday with stops in Ellicott City and Baltimore. By early next week, he plans to have hit every region of the state.

Gansler, who is married and has two teenage sons, is expected to name a running mate in the weeks after his tour, probably in October, he told reporters Tuesday.

Democrats who have had conversations with Gansler about the lieutenant governor post include Baltimore Comptroller Joan M. Pratt, Del. Jolene Ivey (Prince George’s) and Del. Keiffer J. Mitchell Jr. (Baltimore).