D.C. Councilman Jim Graham is poised to become a footnote in the city's political history Monday when lawmakers consider a reprimand of his conduct.

But the looming vote has implications for another lawmaker: Council Chairman Phil Mendelson, who ascended to the city's No. 2 post last year amid another scandal and is navigating one of the first significant tests of his tenure.

"It's never easy to discipline a colleague, and it's never easy to lead that discipline, so Phil finds himself in an unenviable position," said at-large Councilman David Catania. "It's an important moment in his chairmanship."

The D.C. Board of Ethics and Government Accountability set up the moment on Feb. 7, when it said it had "substantial evidence" that Graham had broken the city's code of conduct by offering in 2008 to trade his vote on Washington's $38 million lottery contract in exchange for a company dropping its bid for a development project.

Mendelson has been exploring the next step for lawmakers since the ethics board's ruling through a series of private meetings with legislators.

"Before he imposed his views, he asked me what I thought about the situation," said Ward 7 Councilwoman Yvette Alexander. "He didn't try to sway or lead me in any direction."

And Ward 8 Councilman Marion Barry said he recognized Mendelson was in a challenging spot.

"There's no textbook on how to be chairman," Barry said. "I know it's weighing heavily on his heart."

But as observers watch Mendelson's every move, Mendelson said he isn't focused on the discipline's ramifications for his tenure.

"This is about reprimanding the conduct of an individual," he said. "This is not about me."

And Mendelson said that even considering a public reprimand was counter to his typical approach.

"All of my training is to avoid criticizing a colleague, and this reprimand is everything about criticizing a colleague," Mendelson said. "But the criticism is deserved."

Graham, who has denied wrongdoing and complained that he has been deprived of a right to defend himself, has publicly questioned whether a reprimand is appropriate.

"At its very worst, it was some kind of horse-trading, which happens in every legislative body every hour on the hour," Graham said. "Is this now unethical?"