Governor Charlie Baker has pulled the plug on his push to give condo developers access to the State House lawn, blaming the Massachusetts Historical Commission for changing its position on the controversial project.

His comment Friday evening drew a sharp rebuttal from the commission’s chairman, Secretary of State William F. Galvin, who has insisted the agency never reviewed or approved the request by the developers.

Baker’s decision to back off his quest to let the developers use a sliver of the historic lawn — once the site of John Hancock’s home — to construct window wells for the building, which abuts the property, came just hours before lawmakers were scheduled to take up the issue in a rare Saturday session.

“If the Massachusetts Historical Commission no longer supports the approval it granted in its May 27, 2016, letter to the developers, then the administration would respectively ask the House and Senate to no longer include it as part of the legislation,’’ said Baker spokesman Billy Pitman in a prepared statement.

Galvin, in public statements and in a letter to legislative leaders last week, insisted that an examination of the commission’s 2015 review of the request to make architectural changes to the historic building at 25 Beacon St.showed that the issue of encroaching on the State House lawn was never raised.

“He has repeatedly misstated the facts on this issue,’’ Galvin said Saturday morning. “At some point, a misstatement becomes becomes a misrepresentation. The governor should be capable of understanding the difference.’’

The controversy arose Wednesday when the Globe reported that the governor had attached language to the back of a budget that would grant a permanent easement to the developers of luxury condos in the building, which abuts the west lawn of the State House.

The developers wanted the easement to build enlarged window wells for basements units, three of which would be for au pair suites in the basement of 25 Beacon St., a six-story, 28,494-square-foot mansion. The units are marketed as extra amenities for those considering buying one of six condos selling for between $9 million and $11 million.

Galvin has been highly critical of Baker’s request to assist the developers, saying the easement is only designed to enhance their profits at the expense of giving up a historic property, no matter how small.

Baker has argued the easement would only take up a small slice of land and the state would get some revenue that could be used to support the State House.

Baker and his aides point to a March 2015 letter — which they refer to as a 2016 letter — from the commission to the developers that they say approves an easement. But the commission says the reference in its letter to easement refers to another part of the project, not the land where the window wells would be located.

Galvin said he has been perplexed by Baker’s strong advocacy for the easement, and frustrated by what he says has been the governor’s misrepresentation of the historic commission’s position.

“Even James Michael Curley didn’t try to sell the State [House] Lawn,’’ Galvin said, referring to the legendary rogue political figure who was both governor in the 1930s and Boston mayor for four terms.

Baker aides took umbrage at Galvin’s tongue-in-cheek jab at the governor, who has taken flak for trying to get the easement that would have financially benefited condo developers.

“Governor Baker’s office does not respond to name-calling, and the administration looks forward to working with Secretary Galvin in the future,’’ said spokesman Timothy Buckley.

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Frank Phillips can be reached at phillips@globe.com.