Sigourney singing

She can sing. She sang "Baby, It's Cold Outside" with Buster Poindexter when she hosted Saturday Night Live in the late 80s and was very, very good. So, I think it was an attempt to show that the First Lady was not perfectly professional all the time, because she seemed that way.

She sang in her movie "Snow White". (I remember reading somewhere that she herself had sung in that one scene.) Judging by that song, she actually has a really good and well trained voice.

Glad to hear from the other posters here that Sigourney can sing. Reminds me of Renee Zellweger, who was horrible singing in Bridget Jones Diary, then proved she could sing in Chicago.

It's an old post, but I'll reply anyway.
I don't know if it's true with this movie, but generally "singing badly" is something you usually don't see in films unless it's a really talented singer. They even teach actors how to sing off key as it's not that easy to do (when you first have learned how to sing properly).
So my guess would be that she might have taken some lessons on how to sing in that scene..
And she did sing so awfully!

Of course it was intentional. They were both going to leave the white house. Her because she was no longer the first lady as her husband won't recover, and Dave because Bob alexander threatened to expose him if he had stayed. They first had escaped undetected out of a secret tunnel starting from the white house to outside the gates. And there was had a car waiting for them at the at the end left by Duane. After a heart to heart they decided to have a go and make some real positive changes to the country and as they were heading back to the white house they were pulled over for making a illegal left turn. Once stopped the police recognized them immediately who they were. Dave had to think fast to make them think they were BOTH impersonators of the first couple. And they commented how well they look like them

Then Dave describes a routine they "just performed at a wedding" where the president and the first lady are at club med and the president goes "At 0 10 hundred I want a hour of volleyball. And at O 11 hundred I want a full briefing on the Serbian situation.

Then he describes at that point they go in their finale which is a song from the play "Annie" The sun will come out tomorrow song. In the second chorus the first lady joined Dave on the harmony part but having never sung it before was unsure of the lyrics and was nervous trying to pull it off as just a look alike, not a sound alike. The policeman pulled Dave aside and said "Dave, I'm not going to give you a ticket. I think you'll need all the money you have. Look. You're good. But she needs a lot of work!" in which she returns to the car having embarrassed herself. The movie explained it pretty well to me, but there is the explanation. Enjoy!