Hypothetically, if Sen. Marco Rubio were not an American citizen and could not provide food for his family, he says he would cross the border illegally to come to the United States.

While discussing immigration policy in his new memoir, "An American Son," Rubio (R-Fla.) called for "common decency" in dealing with undocumented immigrants and said that if put in a similar position as those who are fleeing destitution, he would break the law, too.

"Many people who come here illegally are doing exactly what we would do if we lived in a country where we couldn't feed our families," Rubio writes in his book, which went on sale Tuesday. "If my kids went to sleep hungry every night and my country didn't give me an opportunity to feed them, there isn't a law, no matter how restrictive, that would prevent me from coming here."

[Related: Rubio to Obama: Call me maybe?]

Rubio, a member of a political party that has largely opposed efforts to extend a path to citizenship to those in the country without documentation, has been crafting his own version of an immigration reform bill that would let some children of undocumented immigrants avoid being deported.

[Related: Faith a major theme in Rubio's memoir]

Rubio is considered a possible vice presidential running mate for Republican presidential candidate Mitt Romney, who spent the primary season voicing opposition to an immigration plan that would give those who came illegally permanent residency or citizenship without returning to their home country first.