His guardian angel made him do it.

Del. Robert G. Marshall credits a little divine intervention with giving him the final push he needed to call for an impeachment inquiry into Attorney General Mark R. Herring, a Democrat who has charged through a series of controversial actions since he took office in January.

Marshall (R-Prince William) took the rare step Thursday, two days after spotting Herring at a federal appeals court hearing over the state’s ban on same-sex marriage. Herring’s support for overturning that ban and his decision last month to grant in-state college tuition to some Virginians who came to the country illegally as children are among the actions that pushed Marshall to action.

Outside the courthouse in Richmond, which was besieged by protesters, Marshall and his wife bumped into a woman pushing a baby stroller and wearing an “Impeach Herring” button.

“It was my guardian angel saying, ‘Go ahead and do it,’ ” Marshall said in a telephone interview Thursday evening.

Marshall insisted the gesture is sincere and not meant merely as political theater. But opposition from the Republican speaker of the House of Delegates, where the state constitution calls for impeachment proceedings to begin, makes Marshall’s chances slim.

Marshall, one of the legislature’s most outspoken conservatives, filed two resolutions calling for an impeachment inquiry into Herring’s actions. His legal justification, he said, stems from his view that the attorney general violated the state’s constitution as well as the Virginia State Bar’s professional conduct rules for lawyers.

Marshall said that in addition to the marriage and immigration issues, he objects to Herring’s willingness to review letting same-sex couples file joint state income tax returns.

“Three strikes and you’re out, Mark,” Marshall said. “This is a monumental step. I did not take it lightly.”

Herring shrugged off the threat.

“A small handful of legislators seem to remain oblivious as to how the law works, the role of the attorney general, and the publicly stated opinion of top legal scholars,” Herring spokesman Michael Kelly said. Among those scholars, he added, is the author of Virginia’s modern constitution, A.E. “Dick” Howard, who called Herring’s actions “appropriate.”

Marshall hinted during the legislative session earlier this year that he was thinking about impeachment, but House Speaker William J. Howell (R-Stafford) batted down the suggestion.

Howell’s office made it clear again Thursday that he disagreed with the approach.

“The speaker has expressed his concerns regarding the attorney general’s actions but does not believe impeachment is an appropriate or practical recourse at the moment,” Howell spokesman Matthew Moran said.

Marshall remains undeterred.

“The speaker better think twice,” he said. “Has he read my resolution? He maybe should re-read the resolution first. If he still thinks that, he’s in for an education by the people of Virginia.”

Marshall’s resolution calls for two House of Delegates committees, one dealing with the courts and the other with elections, to hold hearings and make a recommendation on whether to impeach.

But with Howell in charge of the House, the resolution is unlikely to go anywhere. Because the legislature is in the midst of a special session to deal with its unfinished budget, the resolution could be considered soon. But Howell will decide which committee will consider it, and that in turn will determine whether the measure makes it onto the House floor for a vote.