The Cuba debate exploded into the Republican presidential race on Friday --and this time it’s personal. Senator Rand Paul, the lone Republican 2016 prospect to back the White House’s normalization plans, picked a high-profile fight with Senator Marco Rubio, the move’s leading national critic, in a series of tweets. The exchange marks a new level of combativeness among the potential presidential field as GOP primary season approaches. EMBED IN ORDERhttps://twitter.com/SenRandPaul/status/545998269524873216 https://twitter.com/SenRandPaul/status/545998696974798848 https://twitter.com/SenRandPaul/status/545999148072202241 https://twitter.com/SenRandPaul/status/545999821694173185 Paul, who publicly came out against the Cuba embargo for the first time in a radio interview this week, also elaborated in a post on Facebook. “I am a proponent of peace through commerce, and I believe engaging Cuba can lead to positive change,” Paul wrote. Rubio, whose parents are Cuban immigrants, has been on a media blitz this week condemning President Obama’s decision to reopen diplomatic relations with the Castro regime in the harshest possible terms.