HTML5 Audio and jQuery

I am trying to use a button to start a track in an HTML5 audio tag using jQuery, but I keep getting an error.

var song = $('#audio');

$('#play').click(function() {
song.play();
});

When I use document.getElementById('audio'), it works, but when using the jQuery selector I get the following error:

Uncaught TypeError: Object [object Object] has no method 'play'

Thanks for any help.