TRYING TO PROTECT HIS left flank, Boston Mayor Marty Walsh jumped into the debate over the MBTA by calling for a local seat on the transit authority’s next oversight board and demanding that the July 1 fare increase be put off until the T is fully operational.

Neither of his requests went very far. Transportation Secretary Stephanie Pollack and Joseph Aiello, the chair of the T’s Fiscal and Management Control Board, rejected out of hand the idea of putting off the long-planned fare hike. And the T governance issue hasn’t even come up for debate yet on Beacon Hill.

What’s more interesting is why Walsh took to Twitter to make the requests in the first place. Walsh’s administration until recently has remained largely on the sidelines as the debate about the T has accelerated. But after the derailment of a Red Line train a week ago, and with City Councilor and mayoral wannabe Michelle Wu (whose Twitter handle is @wutrain) taking issue with T policies on a regular basis, Walsh apparently decided he could be silent no longer.

Wu has forged a strong coalition with transit advocates and disgruntled T riders by diving into the nitty gritty of T operations and drawing on her own personal experience as a transit rider. Sometimes she veers toward the extreme (her call for eliminating T fares entirely was out there) but mostly she makes sound arguments that well-run public transit will reduce congestion, improve the business climate, and help the environment.

Last week, in the wake of the Red Line derailment, Wu stepped up her attacks on business as usual at the T. She never mentioned Walsh in her tweets and comments, but others took note.

“If [Gov. Charlie] Baker and Wu stand on either side of the divide over how to manage rehabilitation of the MBTA, Boston Mayor Marty Walsh is somewhere in the middle,” reported CommonWealth, noting that Walsh continued to support the fare increase while Wu wanted it eliminated entirely. Indeed, Walsh was reluctant to even criticize how the T handled the derailment. “It’s easy to Monday-morning quarterback after the derailment,” he said.

Then the Boston Globe weighed in with a broader story about how Walsh was hewing to the political middle as the City Council is increasingly moving to the left. The story highlighted how Wu wants to charge a fee for residential parking stickers to help address congestion – an idea Walsh dismissed as “an ineffective additional tax.” The story said Walsh believes the city has limited control over traffic.

“How could a mayor have a plan, where would you find that? Seriously, tell me where?” he told the Globe editorial board in April. “People will have cars. What am I supposed to do, stop them? This is a tough issue, I know it is. We’re in the midst of one of the best economic booms in the history of our city, and unfortunately one of the downfalls to that is traffic, and I don’t know what the plan can be.”

While Walsh is correct that traffic is a tough issue, his constituents don’t want to hear that nothing can be done about it. Which may explain why Walsh is now starting to pay closer attention to transportation issues, and becoming more vocal about what to do about them.