(CNN) -- Days before a crucial set of primaries, Democratic presidential candidate Sen. Hillary Clinton is expected to make a surprise appearance on this week's "Saturday Night Live," an entertainment industry source tells CNN.
Sen. Hillary Clinton is running a tight race for Democratic delegates with Sen. Barack Obama.
A spokesman for "Saturday Night Live" would not confirm the appearance, saying only, "It's a live show; anything can happen."
Clinton did not arrive for a campaign charter flight from Dallas, Texas, to Columbus, Ohio, on Saturday evening.
The campaign would not say where she was.