Marty Walsh won’t become mayor until January, but Thursday he made it clear he remains committed to one campaign promise. On Thursday, Walsh, finishing his term as a state representative, sent a key adviser to testify at the State House in favor of a bill meant to make Jonathan Richman’s ode to Massachusetts, “Roadrunner,” the official state rock song. Joyce Linehan, that adviser, wasn’t alone. Others pushing the song included state Senator Bob Hedlund, who cosponsored the “Roadrunner” bill with Walsh earlier this year, state Representative Dan Cullinane and Ellie Marshall, the chanteuse who sang in a latter-day incarnation of Richman’s Modern Lovers. Walsh couldn’t go to the hearing, nor could state Representative Jim Cantwell, who has filed a competing bill pushing Aerosmith’s “Dream On” for the designation. (Nobody testified Thursday for that song.) Comedian John Hodgman couldn’t attend the hearing, though a cousin went and read a letter of support from the Brookline native. In an e-mail later Thursday, Hodgman said he had nothing against Steven Tyler & Co’s classic rocker, but Richman’s tune, which references Stop & Shop, the Massachusetts Turnpike, and Route 128, should not be denied. “Maybe ‘Dream On’ can be named official scream ballad, but not rock song,” wrote Hodgman. “Please not rock song.” What’s next? The Joint Committee on State Administration and Regulatory Oversight will discuss the proposal and decide, likely in the next few weeks, whether to recommend it proceed in the House. State Representative Peter Kocot, co-chairman of the committee, wasn’t tipping his hand. He said he’s a fan of “all good music,” while confessing that he enjoys listening to the J. Geils Band’s 1972 longplayer “ ‘Live’ Full House” while driving back to his home in Western Massachusetts.