The singer, 31, is one of five acts being considered to represent Spain when the 59th annual competition returns on 10 May in Copenhagen, Denmark.
Ruth, who was born in Murcia in the southeast of the country, has confirmed she will perform her own English-speaking track Dancing in the Rain.
She finished in fifth place on the fifth series of The X Factor back in 2008, mentored by judge Dannii Minogue.
The two ladies have teamed up together since the show; Ruth wrote the track Because You Are Beautiful for Dannii's Best Of collection last year.
The Eurovision representative for the United Kingdom — who finished 19th with Bonnie Tyler in 2013 — has yet to be announced.