Lt. Governor Anthony Brown, left, and Attorney General Doug Gansler, right. (Photos by Bill O'Leary/The Washington Post)

Lt. Gov. Anthony G. Brown holds a 2-to-1 lead over his closest rival in Maryland’s bitter Democratic gubernatorial primary race, according to a new Washington Post poll, though most voters say they could change their minds before the June contest.

Brown, who would be the state’s first African American governor, enjoys sizable leads in his home county of Prince George’s, as well as in the Baltimore region, where he runs strongest in a race among three Washington area candidates.

Statewide, 34 percent of Democratic and Democratic-leaning independent voters support Brown in the primary, while 15 percent back Maryland Attorney General Douglas F. Gansler and 8 percent support Del. Heather R. Mizeur. Gansler and Mizeur reside in Montgomery County.

Fully 43 percent say they are undecided, however, and almost six in 10 who have a preferred candidate say there is at least some chance they could switch allegiances before the June 24 primary. Gansler and Mizeur aides played down Brown’s lead Tuesday, saying the race to succeed Gov. Martin O’Malley (D) is wide open and noting that the campaign season has not yet swung into high gear.

“There will be no coronation,” said Gansler spokesman Bob Wheelock.

Selecting Maryland's next governor

Mizeur campaign manager Joanna Belanger said, “ ‘Undecided’ is winning this race.”

The Republican primary is even more unsettled, with nearly six in 10 Republican and GOP-leaning independent voters saying they are undecided. Larry Hogan — a Cabinet member under former governor Robert L. Ehrlich Jr. (R) who entered the race last month, has a statistically insignificant edge over three opponents who have campaigned actively since summer. Hogan has the support of 17 percent of voters, followed by Harford County Executive David R. Craig with 13 percent, Charles County businessman Charles Lollar with 10 percent and Del. Ronald A. George of Anne Arundel County with 4 percent.

Democrats hold a more than 2-to-1 advantage in party registration in Maryland, and Ehrlich is the only GOP governor of the past generation.

Although the Democratic race remains fluid, Brown has several advantages that make him a clear front-runner. Among those most likely to vote in the Democratic primary, Brown has a 22-point margin over Gansler, no smaller than his 19-point edge overall. And more of those who support Brown than Gansler say they “definitely” plan to vote for him.

Brown and Gansler are virtually tied among white Democrats, while Brown leads Gansler among African Americans — a key part of the Democratic electorate — by 31 percentage points. Brown leads among men and women, as well as younger voters and older ones.

Gansler is 10 percentage points ahead of Brown in Montgomery. But Brown is 25 points ahead of Gansler in Prince George’s and 36 points ahead in Baltimore and its suburbs.

While Gansler has spent months faulting Brown for the state’s troubled rollout of its online health insurance exchange, only 5 percent of Marylanders say Brown is “mainly to blame.” Forty-one percent say state or federal health administrators were most responsible, and 11 percent mostly blame O’Malley.

Twenty-four percent of Marylanders say Brown’s part in the health-care rollout will be a major factor in how they vote, and 36 percent say it will be a minor factor. Thirty-seven percent say it will not be a factor.

Overall, 46 percent of Democrats say they have a favorable impression of Brown, while 10 percent say their opinion is unfavorable. Even after seven years as lieutenant governor, however, 44 percent of Democrats have no opinion of Brown, a former Prince George’s delegate who served nearly a year in Iraq as an Army reservist.

“He has a lot of experience because he’s been working with the governor,” said Marion Pauline Robinson, 79, of Hyattsville, a retired grocery store cashier. “He knows how to do this.”

Sal LiCausi, 39, said he is inclined to support the lieutenant governor, but not enthused. “He’s not extraordinary, but he’s not bad either,” said LiCausi, a father of three who works for the Navy and lives in Arnold.

Gansler, a former Montgomery state’s attorney, wants to reduce the corporate income tax from 8.25 percent to 6 percent, to match Virginia’s. Brown and Mizeur say the proposal would sap too much revenue from the state treasury.

Gansler has also sought to play up the notion that he would be Maryland’s first governor from Montgomery, the state’s most populous jurisdiction. More support from his home base could significantly boost his prospects. Fully 55 percent of Montgomery voters are undecided about which candidate to support, more than in other parts of the state.

Statewide, 54 percent of Democratic-leaning residents have yet to form a firm opinion of Gansler. Among those who have, 29 percent have a favorable impression, while 17 percent see him unfavorably.

Voters were divided on whether two recent controversies involving Gansler will affect their choice of candidate. In October, The Post reported that the attorney general had ordered state troopers to regularly speed and run red lights when driving him to even routine appointments. That same month, the Baltimore Sun published a photograph of Gansler attending a high school beach week party where his son was in attendance and where there was apparent underage drinking.

In The Post’s poll, 32 percent of all Marylanders said the state trooper allegations will be a major factor in how they vote this year, while 34 percent say it will be a minor factor. Thirty-one percent say it will not be a factor.

Twenty-six percent of Marylanders said the beach party incident will be a major factor in how they vote for governor, and 28 percent said it will be a minor factor. Forty-two percent said it will not be a factor.

Mizeur, who entered the Democratic race in July, continues to struggle for recognition despite some bold policy proposals and the historic nature of her candidacy. She would be Maryland’s first female governor and the first who is openly gay. She has proposed legalizing marijuana and a broader expansion of pre-kindergarten programs than either of her two Democratic rivals. She also backs a higher minimum-wage increase than Brown and Gansler.

But more than seven in 10 Democrats say they do not yet know enough about Mizeur to have a positive or negative impression. Among those who do, about twice as many are favorable as unfavorable, 19 vs. 9 percent.

As of last month, Brown’s ticket reported having nearly $7.1 million in the bank, while Gansler’s ticket had about $6.3 million. Mizeur had about $750,000 — but not all of that is available to spend on the primary because of rules associated with Maryland’s public financing system, in which she is taking part.

Mizeur is counting on the support of voters such as Barbara Griffith, 72, a retired health-care administrator who lives in Takoma Park. Griffith said she is a fan of Mizeur’s “very progressive stances,” including her advocacy of same-sex marriage and her cautious approach on allowing hydraulic fracturing in Western Maryland.

But those hot-button issues fall far down the list of voters’ priorities. Roughly four in 10 voters say that education, health care, taxes, the economy and crime will be “extremely important” in their vote, but fewer than two in 10 say that about marijuana laws or same-sex marriage.

The poll included both self-identified partisans and those who lean toward each party, with results similar among both groups. The June contests will be limited to those who are registered as Democrats or Republicans.

The survey was conducted Feb. 13-16 among a random sample of 1,002 adult residents of Maryland on conventional and cellular phones, in English and Spanish. The error margin is 5.5 percentage points for the sample of 469 Democratic-leaning voters, and seven points among the 290 Republican-leaning voters.

Peyton M. Craighill and Jenna Johnson contributed to this report.