PORTLAND, Ore. -- A Portland city commissioner called for an investigation and others asked for a resignation Tuesday after Mayor Sam Adams apologized for his relationship with an 18-year-old man.

Adams, a 45-year-old Democrat, admitted Monday that he lied about a relationship with Beau Breedlove, a former teenage intern.

Should He Resign? | Breedlove Statement | Raw Video

City commissioner Randy Leonard, who defended Adams when the allegations first arose, said he's not happy that Adams misled him and the public. He is especially concerned that Adams asked Breedlove to help in the cover-up.

"The part I'm having trouble with is the thing he did was to ask the young man to lie," Leonard said. "That I'm having a hard time understanding."

Portland Police Bureau Chief Rosie Sizer and Multnomah County District Attorney Michael Schrunk have also asked the Attorney General to investigate Adams' actions.

In September 2007, undeclared mayoral candidate Bob Ball accused Adams and Breedlove of having a sexual relationship when Breedlove was 17 years old. At the time, Adams and Breedlove denied having a sexual relationship.

Months later, Adams coasted to victory in the 2008 election, making Portland the largest U.S. city to ever elect an openly gay mayor. He was sworn in Jan. 1.

On Tuesday, however, Adams apologized for lying about the relationship. He first admitted the sexual relationship to the Willamette Week as it prepared to publish evidence of the relationship.

Adams, 45, said he was concerned that people wouldn't believe him that he waited until after Breedlove turned 18 years old to have sex.

The head of the Portland Police Union called for Adams' resignation Tuesday.

"The union's position is that someone who lies, cheats or steals while on duty should not stay employed," said Sgt. Scott Westerman, president of the Portland Police Association.

Leonard said the best way for the city to be able to regain its trust in its mayor is to have an independent investigation of the facts.

"I would very much like to move on," Leonard said. "I would very much like to have Sam as mayor of Portland."

At a news conference Tuesday, Adams was also questioned on the hiring of former Portland Mercury newspaper reporter Amy Ruiz.

Ruiz joined Adams' staff in December as a planning and sustainability policy adviser. At one point, she had confronted the mayor about the relationship with Breedlove. Adams insists her hiring is not linked to her investigation.

FOX 12 political analyst Tim Hibbitts said it's too early to determine how the scandal will affect Adams' future; however, he said it raises many questions.

"First is the question of the sexual affair -- over 18, under 18," Hibbitts said. "The second is question of judgment. The third is a question of abuse of power, related to the position of Mrs. Ruiz in the sustainability office."

Adams said he did not plan to resign, but said he would consider it if it's in the city's best interests.

Mayor Asked To Resign By Police Union Head