Rubio donors say they have been flooded with calls, texts and e-mails in recent days from uncommitted patrons now eager to make and bundle contributions to help him. In addition, his comments against abortion during the debate have also allowed Rubio to emerge as one of the GOP’s leading voices on the issue — drawing sharp criticism from Clinton, which is always a plus in the Republican primary.

Rubio, 44, emphasized during the debate in Cleveland that he has never advocated allowing abortions in cases of rape or incest and said the current generation would eventually be viewed as “barbarians” for legalizing the procedure. The remarks elevated his standing among social conservatives, but Democrats say it undermines his pitch as a new-generation Republican.

The issue also underscores a broader predicament facing the son of Cuban American immigrants if he wins the Republican nomination: how to portray himself as a representative of the “new America” while defending views on gay marriage, drugs, abortion, Cuba and other issues that are out of step with much of the public, particularly younger voters.