At a news conference called yesterday to announce a citywide book drive, Baltimore Mayor Martin O'Malley paused and acknowledged a young man with a video camera who has become a constant presence at his public events.

"Everybody wave to Doug Duncan's camera," O'Malley told the audience, referring to his Democratic rival for governor, who had dispatched the campaign aide.

It is hardly the only thing Duncan is doing these days to get in O'Malley's face. The Montgomery County executive has challenged O'Malley's support of slot-machine gambling. He has questioned his commitment to the environment. And just last week, Duncan traveled to Baltimore to raise doubts about an O'Malley-backed plan to publicly finance a hotel there.

O'Malley, for the most part, has tried to brush off the barbs, focusing his firepower on Gov. Robert L. Ehrlich Jr., the Republican he hopes to replace next year. But yesterday, O'Malley pushed back with unprecedented vigor, calling Duncan "kind of desperate" and circulating new poll numbers that call into question Duncan's strength in his home county.

Aides to O'Malley, who has a sizable statewide lead in early polls, have expressed frustration with Duncan's attacks, which they characterize as distortions.

"It's unfortunate that over the past few weeks and months, Doug Duncan has waged an increasingly negative and desperate campaign," said Jonathan Epstein, O'Malley's campaign manager. "He sees the same numbers as everyone else is seeing. . . . He knows the only way to close the gap is by firing misleading and inaccurate negative attacks against Martin O'Malley."

In an interview yesterday, Duncan said he is trying to raise issues important to the state -- and accused O'Malley of trying to duck them. "This campaign is going to be about issues and ideas, and whoever has the best ideas is going to win," Duncan said.

Scott Arceneaux, Duncan's campaign manager, said yesterday's events showed that "the mayor clearly wants a coronation and not an election."

The back-and-forth was prompted by a letter sent Tuesday to O'Malley's campaign. In it, Duncan challenged the mayor to join him in demanding that Ehrlich apologize for holding a recent fundraiser at a golf club that has had no black members in its 127-year history. O'Malley's campaign did not respond to the letter, and Ehrlich has not responded to Duncan's demand for an apology.

Asked about it yesterday, O'Malley told reporters that he has not held events at the Baltimore club and will not. But he also used the occasion to take a swipe at Duncan.

"He's kind of desperate and looking for opportunities to get his message out," O'Malley said.

Also yesterday, O'Malley's aides shared results of a poll conducted for his campaign with prominent Maryland Democrats. A memo about the findings was provided to The Washington Post by an O'Malley supporter in Montgomery County.

The poll, conducted last month by the GarinHartYang Research Group, showed O'Malley leading Duncan statewide, most significantly in the Baltimore region. The mayor's margin of support there was shown to be far greater than the support Duncan enjoyed in Montgomery.

"The survey finding is significant," the polling memo said, "because it suggests that Duncan will be hard-pressed to achieve the strong electoral support he requires from Montgomery County to make up for O'Malley's strong showing in the Baltimore region."

Aides to Duncan have acknowledged that he will need to carry Montgomery by a substantial margin to win the Democratic nomination. But Arceneaux played down O'Malley's numbers yesterday, saying he does not put much stock in polls taken more than a year before the primary.

Arceneaux rattled off several figures related to Baltimore's struggling schools and its crime rate, adding: "Those are the numbers we're going to be talking about."

O'Malley aides contend that much of Duncan's talk about the mayor's positions has been misleading. Duncan, for example, has said O'Malley "stands with Ehrlich" on legalizing slot-machine gambling. O'Malley has said he would support a limited number of slot machines at certain racetracks, including Pimlico in Baltimore. Ehrlich has backed more expansive plans.

Baltimore Mayor Martin O'Malley said his rival is "kind of desperate."