(CNN) Minnesota Democratic Sen. Al Franken returned to Capitol Hill Monday for the first time since reports of sexual harassment against him were earlier this month, apologizing for letting people down and vowing to regain lost trust.

At a brief news conference outside his Senate office on Monday morning, Franken was apologetic and said he planned to get back to work.

"To all of you, I just want to again say I am sorry. I know there are no magic words that I can say to regain your trust and I know that's going to take time," he said.

Franken also said he could not "speculate" whether more women would come forward with similar allegations about his behavior.

"If you had asked me two weeks ago would any woman come forward with an allegation like this I would have said no," he said. "This has been a shock and it's been extremely humbling. I am embarrassed. I feel ashamed. What I'm going to do is I'm going to start my job, I'm gonna go back to work."

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