The 26-year-old, who was killed in a shootout with police last week, and his younger brother, Dzhokhar, 19, are the primary suspects in the attack, which left three dead and more than 250 wounded.
That was a safe assumption until the Florida primary, when two things happened: Romney proved he could attack his opponents, and Romney, who had never pulled even 40% of primary voters in other states, won 47%.