Upated 11:31 pm, July 12, 2018

Some two years after Boston Mayor Marty Walsh promised to institute the first ever regulations requiring the public disclosure of lobbying efforts directed at city officials — Walsh has vetoed an ordinance that would make those transparency measures law.

In a letter to City Council members Thursday, Walsh said he will veto a city ordinance requiring lobbying disclosure passed by the Council two weeks ago.

At the same time, the mayor has submitted a new proposed ordinance that Walsh said in the letter will make for better legislation. His new proposal includes a new commission to ensure compliance with the rules and investigations of non-compliance.

Walsh wrote that the Council’s ordinance “does not provide the City with strong enforcement tools,” — reiterating a claim he’s made that the Council’s version was too weak.

But the Walsh administration’s “weakness” claim is debatable: For one thing, the mayor submitted his proposed reforms in the form of a home rule petition, which requires approval by the state legislature, where prospects of passage are far from certain.

The City Council’s ordinance, by contrast, could have become law immediately without any state approval.

And while Walsh’s home rule petition included higher fines for noncompliance that do require state approval — it also included a broad exemption for lobbying expenditures of $2,500 or less — allowing the potential for lobbying by well-connected players on a “pro bono” basis.

The mayor says his veto is intended not to kill the effort but to resume negotiations over a new city ordinance.

City Councilor Michelle Wu, a lead sponsor of the Council bill, told WGBH News that she disagreed with the mayor’s characterization of the Council bill.

“I believe the ordinance the Council submitted and passed is a strong piece of legislation,” Wu said, adding that she nonetheless looks forward to working with the Walsh administration on possible revisions.

City Council President Andrea Campbell said in a statement issued shortly after the veto that she welcomed “most of the Mayor’s amendments,” and said “I look forward to getting this done.”

Walsh will not veto a separate home rule petition passed by the Council that is largely identical, but includes higher fines for non-compliance.

Read Walsh's letter to the City Council: