Tina performed all eight songs in the Irish national heats on RTE's Saturday evening entertainment series The Likes of Mike, where she sang four songs in English and four in Irish. The result was decided, for the first time since 1967, by a public postal vote in which "Cross Your Heart" won by a landslide with 16,686 votes, 11,000 clear of the runner-up "Is Liom É".
The song is moderately up-tempo, with Reynolds using a number of childhood rhymes ("cross your heart and hope to die" and "sticks and stones wouldn't break my bones") to communicate to a would-be lover how serious she is about a potential relationship, with the contrast between the serious intention and the playful nature of the rhymes being drawn out throughout the lyrics. She sings that, although her heart has been broken before, she has no intention of giving up on love now. She also reminds her lover that "so many hearts are broken by one little lie".