Utah Attorney General Mark Shurtleff, who has been open about his interest in challenging Sen. Bob Bennett in the GOP primary next year, said Thursday afternoon that an announcement about his 2010 plans will come on May 20 at a press conference in Salt Lake City.Shurtleff told a local Utah television station last week that he wants to run for Senate, but that his wife has asked him for time to talk him out of making the race. On Thursday, as he was preparing to leave on a trade mission to Israel with Gov. Jon Huntsman Jr., Shurtleff said he’s “99 percent sure— of what his decision will be.Shurtleff — who won a third term as attorney general last year and isn’t up for re-election until 2012 — could represent a serious threat to Bennett because of his high name identification and his proven ability to campaign and raise money statewide. While Bennett isn’t considered vulnerable on his right flank, some Utah Republicans have said that the attorney general might gain traction if he runs on a strict anti-Washington message.In recent months Shurtleff has criticized Bennett for being a key Republican voice in the passage of the $700 billion Wall Street bailout bill and the creation of the Troubled Asset Relief Program last October.Bennett had about $625,000 in the bank at the end of March while, according to state disclosure records, Shurtleff ended 2008 with about $72,000 in cash on hand.