"Marco Rubio scares me," wrote Steve Schale, a Democratic strategist in Florida. "If you're a Democrat, he should be the one you don't want to face."
The New York Times reported Schale's memo last May. It's still valid, and a close look at the Republican field reveals that Rubio's chances of winning the nomination continue to grow.
Sure, in national polls averaged by the website Real Clear Politics, TV celebrity Donald Trump still holds a lead with 23.4 percent, while retired surgeon Ben Carson places second with 19.1 percent.
But both are so clearly unqualified to be president that it's hard to imagine the Republican Party -- even in its divided and dysfunctional state -- actually nominating either one.
If that's true, then who will fill the vacuum? The GOP will not nominate "None of the Above." Someone will be chosen in Cleveland next July.
Early on, a lot of smart money was on Gov. Scott Walker of Wisconsin, a fresh-faced Midwesterner untainted by Washington politics. Turns out he also lacked preparation and judgment. He was gone by autumn.
Former Florida Gov. Jeb Bush is still around, and with $100 million or so in the bank, he cannot be counted out. But this son and brother of former presidents has consistently underperformed and underwhelmed as a candidate. He seems to have trouble answering the question that bedeviled Ted Kennedy in his 1980 campaign: "Why do you want to be president?"
So Jeb's running fifth, with an average score of 7.3 percent in national polls. Moreover, it's hard to see things changing for Jeb, to see him transform in the next few months into a more dynamic and compelling figure.
Former business executive Carly Fiorina is running fourth at 8.3 percent, and could make it into the finals. But the burst of enthusiasm generated by her two debate performances has cooled off, and she lacks the organizational assets to compete on March 1 -- only three weeks after New Hampshire, when 13 states hold primaries or caucuses.
The rest of the field? Ted Cruz and Mike Huckabee are simply too conservative, even for today's GOP. Chris Christie and John Kasich are more broadly competitive, at least on paper, but neither one has gained much traction. Rand Paul is out of step with just about everyone.
That leaves Rubio. He's running third, at 9.9 percent, and he scares Democrats for a reason. Several reasons, actually.
We have always believed that the ability to tell stories and relate to voters on a personal level is one of the most valuable assets a presidential candidate can possess. That's why Hillary Clinton introduced herself at the Democratic debate as "the granddaughter of a factory worker and the grandmother of a wonderful 1-year-old child."
Rubio is the best storyteller in the Republican field. The tales he tells -- of his father the bartender and his mother the hotel maid -- send a powerful message: I know what your lives are like. I'm just like you.
One of Rubio's finest moments came during the second GOP debate, when he answered Trump's jibe that candidates should speak only in English. He described the wisdom his grandfather had passed down to him, about the blessings of living in America.
"He taught me that in Spanish, because that was the language he was most comfortable in," Rubio said. And he will continue to speak that language, he insisted, in order to reach voters directly "who are trying to achieve upward mobility."
Democrats won 71 percent of the Hispanic vote in 2012 and are counting heavily on expanding their advantage with that community next year. The Spanish-speaking son of a maid and bartender could pose a major threat to that strategy, especially in Florida, the second-most important state in American politics after Ohio.
At 44, Rubio radiates youthful energy and provides a stark contrast to Clinton, who will be 69 on Election Day. Jack Kennedy, Bill Clinton and Barack Obama -- all elected in their 40s -- testify to the appeal of a candidate who embodies "a new generation of Americans."
Rubio's fundraising has lagged, but Politico reports that he is making inroads with big GOP money sources like casino magnate Sheldon Adelson.
Now comes the hard part. As Rubio gets closer to the nomination, the spotlight will get hotter, the media scrutiny will get tougher and the attacks from his rivals will get sharper.
But if he makes it through this period, the Democrats should be scared. Rubio is definitely the Republican they don't want to face.