UPDATE 8 p.m.
Mitt Romeny won all 20 delegates in Sunday's Puerto Rico Republican presidential primary.
To date, Romney leads the overall race for delegates with 521. Rick Santorum follows with 253; Newt Gingrich has 136 and Ron Paul has 50.
Next up: the Illinois GOP primary on Tuesday, with 54 delegates at stake.
The latest cross-country stop on the GOP presidential campaign trip is Puerto Rico, which holds its primary today.
Both Mitt Romney and Rick Santorum campaigned in Puerto Rico this past week, in search of the island's 20 delegates to the Republican national nominating convention. Romney got a key endorsement from Puerto Rican Gov. Luis Fortuno, who is pushing hard to make the island the 51st American state.
This November, not only will Puerto Ricans vote for president, but they'll also decide the direction of their island's political status: statehood, independence or no change.
Romney and Santorum will watch the results from Illinois, the site of the next big primary, which is slated for Tuesday. Much of the early public polling shows Romney ahead in Illinois, with particular strength among suburban voters in and around Chicago.