Sen. Marco Rubio may be a star in Florida and the D.C. beltway, but he's still largely unknown nationally, a Latino Decisions poll shows.

But Rubio has better traction than another Hispanic lawmaker who could be on the VP list, New Mexico Gov. Susana Martinez. Rubio has a higher favorability among Latino voters (26% compared to 16%), and fewer Latinos have “never heard of” Rubio.

The pollsters conclude: "Although placing a Latino on the GOP ticket may in fact have a positive impact on Latino voters. Given that President Obama enjoys a nearly 50 percentage point favorability advantage over all Republican contenders among Latino voters at this point, this move may prove to  be too little and too late for a party struggling to revitalize its image with the Latino electorate."

Poll is here.