After exploring a Senate campaign for months, Tucson City Councilman Rodney Glassman (D) resigned from his position and made his bid official Tuesday night.

Glassman, a 31-year-old potential self-funder, is the likely Democratic nominee to take on either Sen. John McCain (R-Ariz.) or his primary rival, former Rep. J.D. Hayworth (R-Ariz.). His move to formally enter the Senate race comes less than 24 hours after attorney and pecan farm owner Nan Stockholm Walden’s decision to pass on the race.

Glassman announced his campaign upon resigning from the city council, per Arizona’s resign to run law.

He is considered the underdog in a race against either McCain or Hayworth, according to a recent poll done by Research 2000 for the liberal Web site Daily Kos, which found Glassman trailing both Republicans by double digits.