So much for Senator Rubio supporting immigration reform, Hillary Clinton and Joe Biden would both crush him among Hispanics

I am not sure why this polling doesn't include Ted Cruz for a comparison.  It would be very interesting to see if Cruz did as well a Rubio despite his opposition to the immigration reform plan.  From Politico:

. . . The survey, by Latino Decisions, also revealed Republican candidates continue to significantly trail among Hispanic voters, with even champions of immigration reform like Sen. Marco Rubio (R-Fla.) and former Florida Gov. Jeb Bush significantly behind top Democrats.That deficit could again prove significant in 2016, when the pollsters estimate that the Hispanic vote will approach 12.5 million. In 2012, exit polls suggested 71 percent of Hispanic voters broke for President Obama.
According to the survey, Clinton remains the most popular candidate among the Hispanic electorate, mirroring other recent national surveys. The former first lady is seen positively by 73 percent of likely Hispanic voters, while 17 percent have a negative view. . . .
Rubio, unsurprisingly, would begin with a major deficit in a head-to-head matchup with Clinton. According to the poll, Clinton would win Hispanic voters 66-28 percent, with 6 percent remaining undecided. Biden fares nearly as well, holding a 60-28 percent advantage over Rubio with 12 percent undecided. . . .