A top lieutenant to Speaker Robert A. DeLeo will resign her Revere-based seat to take a government relations post this month, she said Thursday, removing from House leadership a chief advocate of a casino in her hometown.
Representative Kathi-Anne Reinstein, first elected to the House in 1998, said she will step down to become government affairs manager for the Boston Beer Co.
The company, which brews Samuel Adams beer, has been shopping for a government affairs executive for months, eliciting interest from several big names in local politics.
Reinstein’s decision comes at a pivotal time in the ongoing debate about where to site a Massachusetts casino, with a vote on the proposed facility scheduled for next month.
The Democrat has been a vocal proponent of the Suffolk Downs and Mohegan Sun facility in Revere, after East Boston residents last year voted down such a venue in their neighborhood.
She joins a growing parade of lawmakers, particularly in the House, who have left the Legislature in recent years to accept government affairs and lobbying jobs.
Both Westfield and Dorchester have special House elections slated for April, as does the north-of-Boston state Senate seat vacated when Katherine Clark won a congressional seat.
In a note to supporters on Thursday, Reinstein described the “emotional beginning” of her political career. In 1998, she won the seat long held by her father, who had died of cancer earlier that year.
Reinstein wrote that she would be “unable to actively participate” in the Feb. 25 city referendum on a host community agreement with Mohegan Sun. But she urged residents to “join me in voting” in favor of the pact.
A longtime DeLeo friend, Reinstein played a prominent role in helping him cobble together the necessary votes to win the speakership in 2009.
Since then, she has been a close deputy, serving as second assistant majority leader and frequently voicing the leadership line on issues.
Reinstein’s resignation takes effect Jan. 17.
She declined to be interviewed, referring instead to her note to supporters.
Jim O’Sullivan can be reached at Jim.OSullivan@globe.com. Follow him on Twitter at @JOSreports.