From a Maryland Gazette article entitled Duncan takes shot at O'Malley:
(SNIP)Steve Kearney, O'Malley's spokesman, did not try to deflect Duncan's criticism.
"The truth is that, after three years of gridlock, the mayor thinks a reasonable, responsible compromise is possible to protect the thousands of jobs in Maryland's horseracing industry, to keep the Preakness in Baltimore, and use some funds for school construction," Kearney said. "It's time to get this behind us and move on to the other important issues facing our state."
Here's the whole paragraph with the key sentence in bold:
There will be a big story in the Post either tomorrow or Thursday that credits Governor Ehrlich's staff for creating and spreading the nasty and untrue rumor about our Mayor and his family. Steve asked me to contact you to see if you could show your disgust by calling into WBAL Radio after the story hits. The guys on WBAL obviously could try to protect Ehrlich, so we need as many folks as possible to call 410-467-WBAL. I will e-mail the story to you as soon as it hits and read it carefully and then call in and raise hell. Don't call in until after the story is published in the Washington Post - It is top secret!
The letter sounds like a mass email to Maryland Democrats to seminar call WBAL so they would likely know Steve (Jost) from his party activites. But it's also possible that it's a mass email to Baltimore City employees that would likely know Steve Kearney as the mayor's spokesman.
I'm more inclined to think it's Steve Kearney because the letter describes O'Malley as "our mayor". I'll see if I can dig out his email address.