With no serious opposition left, the former Massachusetts governor easily won Tuesday's primary in Kentucky.
Romney also won Tuesday's Primary in Arkansas.
Virtually assured of the party nod, Romney has been in general election mode for weeks. He's been spending much of his time fundraising and focusing on Democratic President Barack Obama.
A total of 75 delegates were at stake in Kentucky and Arkansas. Romney started the day with 992 delegates - 152 shy of the 1,144 needed to claim the nomination.
Romney is on pace to reach the magic number next week, when Texas voters go to the polls.