Steny Hoyer (Photo by the Associated Press)

House Minority Whip Steny H. Hoyer (D-Md.) plans to endorse Lt. Gov. Anthony G. Brown (D) as Maryland’s next governor on Monday, adding another high-profile name to a growing list of early Brown supporters in a competitive Democratic primary.

“I am proud to support Anthony Brown for governor because I know he will use his experience and passion to continue bringing jobs and opportunity to all Marylanders, from Southern Maryland to Prince George’s County and across our state,” Hoyer said in a statement to The Washington Post, in which he says he has known Brown for years and credits him with having “worked tirelessly” on behalf of Maryland.

Brown’s campaign has started promoting two events on Monday, in Waldorf and Greenbelt, where it says “an exciting campaign announcement” will occur. Hoyer, the No. 2 Democrat in the U.S. House of Representatives, is expected to attend both events.

The announcement of Hoyer’s backing will be the latest move by the Brown campaign intended to generate a sense of momentum before Brown’s chief rival, Attorney General Douglas F. Gansler (D), enters the 2014 race.

Gansler plans to formally announce his bid for governor in September. His team is calculating that most voters won’t tune into the contest before then. But Gansler has become increasingly visible as an all-but-declared candidate, launching a statewide tour to promote his priorities for the race.

On Wednesday, Gansler, Brown and Del. Heather Mizeur (D-Montgomery) — another Democratic hopeful — all made the rounds at a clam bake in Crisfield, as did several Republicans who have either announced gubernatorial bids or are considering doing so.

Gansler has said he expects plenty of endorsements but has no plans to announce any before becoming an official candidate in September.

Besides Hoyer, Brown’s backers include two other members of the Maryland congressional delegation: Reps. Donna F. Edwards and Elijah Cummings.

Gov. Martin O’Malley (D), whom Brown is seeking to succeed, has also endorsed Brown, as has Baltimore Mayor Stephanie Rawlings-Blake (D) and 70 other municipal officials.