Clinton's campaign was pretty concerned with Rubio's allure, emails show

  • Sen. Rubio after paying his respects to the victims of the Pulse nightclub shooting, June 16, 2016.

    Sen. Rubio after paying his respects to the victims of the Pulse nightclub shooting, June 16, 2016.  (ap)

  • Republican candidate Sen. Marco Rubio at a rally Sunday, Feb. 21, 2016, in Franklin, Tenn.

    Republican candidate Sen. Marco Rubio at a rally Sunday, Feb. 21, 2016, in Franklin, Tenn.  (ap)

In February of 2015, top strategists for the Hillary Clinton campaign were concerned about the emerging candidacy of Sen. Marco Rubio and his appeal to not only Hispanics but conservative voters, according to newly-hacked campaign emails first reported by Politico.

Joel Benenson, the chief strategist for the campaign, wrote an email to other top Clinton brass about his "anxiety thought of the day," specifically referencing the Florida Republican’s potential appeal to new voters, centrists, and Latino voters — while keeping his credibility with conservative voters.

"I’m beginning to worry more about Rubio than the others," Benenson wrote to an inner circle of Clinton officials. "He has stronger right-wing cred than Jeb and he’s finding a way to the middle enough for now and he will be the most exciting choice to Republicans."

"[Rubio] could pose a real threat with Latinos, etc." Benenson wrote.

Another Clinton strategist, Mandy Grunwald, acknowledged that Rubio, a Cuban-American, was "very inspiring at his best" but dismissed his overall potency as a presidential candidate.

"Feels kind of like a lightweight in a lot of interviews — but I take your point," she replied to Benenson in the group email chain.

After Rubio formally announced his candidacy in the spring of 2015, a speech that highlighted his family's narrative and his working-class background, the Clinton campaign again took notice.

Campaign aide Christina Reynolds sent an email to a Clinton rapid response email group with some "Rubio notes" on his announcement.

"He gives a good speech and sounded much more reasonable, populist and accessible than much of the rest of the GOP field," Reynolds wrote. "Felt more like an inspiring Democratic speech than a GOP candidate, outside of foreign policy, repealing Obamacare and choice."

Reynolds also noted that the 45-year-old senator made a generational argument not just against his former mentor and rival former Florida Gov. Jeb Bush, but Secretary Clinton as well.

"Lots of references to "our generation" (I.e. Him and younger voters) vs. "their generation" (them being us, Jeb, his opponents, Washington)," Reynolds wrote.

In a separate email back and forth, Communications Director Jennifer Palmieri, a respected Democratic operative of several campaigns, responded to Rubio's subtle hit at Bush and Clinton.

“Don't see reason to react here,” Palmieri, wrote in a reply.

“Agreed. Let them take it as an attack on Bush,” Grunwald responded.

Despite increasing expectations and momentum following a solid showing in the South Carolina primary, Rubio could not recover from a poor performance at a New Hampshire debate.  

The death blow to his nascent presidential aspirations for this cycle came to an end after eventual GOP presidential nominee Donald Trump soundly defeated the West Miami native in the Florida Republican primary.

Rubio, now running against Democratic congressman Patrick Murphy to regain his seat in the U.S. Senate, is leading in recent polls. However, in a campaign stop in Miami Tuesday, Clinton took a shot at Rubio, with Murphy in the crowd.

On the issue of climate change, a top one for many south Florida voters, Clinton criticized Rubio for his retort that he was "not a scientist" when asked about the topic.

"Well, why doesn't he ask a scientist?" Clinton said, with former Democratic presidential nominee Al Gore sitting behind her on the stage.

"Maybe, then, he would understand," she said.

Serafin Gomez is a White House Producer for FOX News Channel, who also covered the 2016 election as a Special Events & Politics producer and former special campaign correspondent for Fox News Latino. Fin formerly worked as the Miami Bureau Producer for Fox News Channel where he covered Florida Politics & Latin America. Follow him on Twitter: @Finnygo