Both U.S. Rep. Ileana Ros-Lehtinen, R-Miami, and her Democratic challenger, Annette Taddeo, have pledged to fight Florida's proposed constitutional ban on gay marriage. Amendment 2 will be on Florida's ballot in November. If passed, it would amend the state constitution to ban gay marriages and civil unions, as well as publicly recognized domestic partnerships. ''Most [Amendment 2 supporters] would like to frame it as a gay issue,'' Ros-Lehtinen said Sunday at Miami Log Cabin Republicans club meeting. ``It's not that at all. Most of the domestic partnerships in Florida are heterosexual.'' Taddeo, the Democrat challenging Ros-Lehtinen in this fall's election,...