Republican presidential candidate Ted Cruz took two swipes at Marco Rubio at Tuesday's debate that offered hints of a looming showdown between the rivals.

Cruz didn't refer to Rubio by name when he warned against Republicans becoming the “party of amnesty” on immigration, nor when he said, unprompted, that he'd seek to rectify the country's finances by eliminating “corporate welfare like sugar subsidies.”

But the connection was clear to political observers. Rubio, of Florida, has faced conservative criticism for his immigration overhaul work, his backing of sugar subsidies, and his ties to sugar magnate Pepe Fanjul.

Rubio ignored the veiled jabs on stage. Asked about Cruz's sugar comments on Good Morning America on Wednesday, Rubio said he's prepared to end the U.S. program when other sugar-producing companies end theirs. In the meantime, he said, he's “not going to destroy an American industry that employs people in my state.”

Tension has risen between the candidates—both 44-year-old Cuban-American freshman senators—as they battle for third place behind front-runners Donald Trump and Ben Carson. Cruz set his sights on Rubio before the debate by backhandedly complimenting him as a formidable “moderate.”

Rubio campaign manager Terry Sullivan scoffed at the “moderate” label after the debate.

“It's crazy. Absolutely, positively most ridiculous thing I've ever heard in my entire life. Marco Rubio is the conservative's conservative,” Sullivan said, referring to Rubio's high so-called purity scores from conservative groups like the American Conservative Union and National Rifle Association.

But Cruz spokesman Rick Tyler hinted there's more where that came from.

“We've moved on to 'I'm for this and they're for that,'” Tyler said after the debate. “In the end, all campaigns are about contrast. So you draw the contrast and let people decide.”

“Cruz turned in a very solid, substantive debate. You can argue that Rubio did as well,” he added. “So then it is, what is the substance of those two policies, and who's been consistent on those policies? And I think we win that.”

Alison Elkin contributed to this report.