WASHINGTON -- An upbeat Rick Santorum barreled into Puerto Rico Wednesday in pursuit of another campaign-bending victory in a Republican presidential race where suddenly no primary is too minor and no delegate is conceded.

Mitt Romney, meanwhile, has put nearly $1 million into television advertising in Illinois, the next big-state showdown.

"If we keep winning races, eventually people are going to figure out that Governor Romney is not going to be the nominee," said Santorum, eager to build on Tuesday's victories in Alabama and Mississippi.

Romney in turn dismissed Santorum as a "lightweight" as far as the economy is concerned.

Romney will travel to Puerto Rico Friday, after two days in New York fundraising.

Newt Gingrich, despite losing twice in the South, a region he hoped to own in the race, showed no sign of abandoning his fading campaign.

That presumably suited Romney fine, but not so much Santorum, who is eager for a race in which he is the sole challenger on the right to Romney.

Santorum's primary victories in Mississippi and Alabama were the product of a wellspring of conservative support that overcame Romney's overwhelming organizational and financial advantages.

And despite the two defeats, Romney remains the faraway leader in the delegate chase. Incomplete returns showed him actually adding one or two to his advantage because of overnight caucus victories in Hawaii and American Samoa.

That division -- headline-grabbing primary victories versus routine accumulation of delegates -- emerged as an increasingly significant point of contention as Romney, Santorum and Gingrich selected facts and spun theories designed to put their own hopes in the best light.

Romney's aides point out that he has more than half the delegates picked so far, and he has said he's on track to win the nomination before the party convention opens in August.

Santorum's camp outlined a strategy that relies on increasing strength in later primaries, coupled with outmaneuvering Romney in caucus states where the front-runner showed early strength but delegates have yet to be picked.

Gingrich's campaign countered with a memo Tuesday that said Louisiana's primary on March 24 is the halfway point in the campaign, and he had succeeded in a goal of blocking "an early Romney nomination."