When Hillary Clinton appointed Amanda Renteria as her political director, the first Latina to serve as a Senate chief of staff added another historic achievement to her biography, NBC News reported.

But in practical terms, the Democratic frontrunner's choice can also be seen as yet another move to secure votes from Hispanics, who will make up a key demographic in the 2016 White House race.

It is also a demographic Marco Rubio, the newly announced GOP candidate, has been counting on.

As the son of Cuban immigrants, the Florida senator's ties to the Latino community are as evident as those of his Republican challengers -- Ted Cruz, a fellow Hispanic, and Jeb Bush, whose wife was born and raised in Mexico. But because of what some have called a flip-flop on immigration policy, Rubio has so far not been able to catch up to Clinton when it comes to popularity among Hispanics.

Rubio "holds little appeal to Latino voters," CNN's Raul Reyes noted in an opinion piece.

In 2013, as a member of the so-called Senate "Gang of 8," he helped craft a bipartisan immigration bill that included a path to citizenship for the nation's estimated 11 million undocumented immigrants, Reyes noted. But he later distanced himself from the legislation and now favors a piecemeal approach, starting with securing the border, the CNN commentator added.

"His retreat on immigration means that Rubio has missed an opportunity to set himself apart from most of the presumptive Republican presidential candidates," Reyes judged.

More conservative Hispanic groups, however, do not agree with that assessment, Bloomberg noted. Adryana Boyne, the national director of the conservative Hispanic outreach group VOCES Action, for example, said she sympathized with the senator's approach.

"I would say that he saw the reaction (to the bill) and listened to constituents and Americans who were reluctant to have comprehensive immigration reform," Boyne argued.

In fact, Rubio's record on immigration compares rather favorably to Clinton's, insisted Brent Wilkes, the national executive director of the League of United Latin American Citizens, given that her husband, President Bill Clinton, signed off on "some of the worst anti-immigrant legislation in a generation" in the 1990s.

"To try to compare and contrast Rubio's record with Hillary Clinton on the immigration question and pretend that Hillary's going to win that fight outright, I think, is a mistake," Wilkes said.