"He's tremendously smart, extremely serious and impeccably polite," Delaney press secretary Will McDonald said.

Moring came in the door of the Delaney campaign as a volunteer interested in climate change policy. But he quickly distinguished himself as an unflappable jack-of-all-trades, McDonald said. "He probably has a very low resting heart rate," he said.

When a Gansler supporter attempted to block Moring from recording the candidate's interview with reporters, Moring asked, "Can you get your hands off me, sir?"

Campaign aides to Montgomery County Del. Heather Mizeur, the other Democrat in the three-way primary race, said they run into Moring at events when Mizeur and Gansler appear together.

"He is incredibly professional and courteous," campaign manager Joanna Belanger said. "It's the insider etiquette with trackers."

So far, Moring's hours of footage have not affected the contest.

Gansler received negative publicity for being at a party where teens said there was underage drinking, but a photo of him there published in The Baltimore Sun was initially posted on Instagram by one of the young party-goers. Gansler also took heat for a secretly recorded remark he made about Brown, but Brown's campaign has not been linked to the taping.

"For all the bravado of the Anthony Brown campaign, the fact that they have a tracker on Gansler suggests they still consider him a serious threat," said Todd Eberly, a political scientist at St. Mary's College.

Eberly said that of all the candidates running for governor, it makes sense to put a tracker on Gansler, who has described himself as "not a smooth-talking politician."

"Gansler frequently speaks and bypasses that internal filter that many of us have between our brains and our lips," Eberly said. "Now, in politics, you can't afford to be human because someone is there recording everything you said."

None of the Republicans running for governor use a tracker, and neither does Mizeur. Wheelock said Gansler advisers have debated whether the campaign needs to hire its own tracker, despite Gansler's distaste for the practice. "Is it a necessary evil?" Wheelock asked.