He has. Go to Governor Mitt Romney On Fred Thompson Withdrawing His Candidacy for the following statement:
Boston, MA – Today, Governor Mitt Romney issued the following statement on former Senator Fred Thompson withdrawing his candidacy for President of the United States: "Throughout this campaign, Fred Thompson brought a laudable focus to the challenges confronting our country and the solutions necessary to meet them. He stood for strong conservative ideas and believed strongly in the need to keep our conservative coalition together. Ann and I would like to extend our best wishes to Fred, Jeri and their family and congratulate them on their efforts during this campaign."
Uh, notice that I posted that BEFORE Romney made his statement.
Nice statement by Mitt. Sorry that Fred quit.