Democrats fundraise and campaign by exploiting concerns about right-wing extremism. But at least at the moment, what they apparently fear most is the rise of a candidate who could potentially poach enough of their supporters to beat them in 2016.

Rand Paul has not yet formally announced he is running for the Republican nomination. But with a lead in GOP polls and already laying the foundation for the infrastructure of a campaign, the junior senator from Kentucky is considered the early front-runner, one who is transparent about his desire to appeal to a broad range of voters—and that has Democrats worried.

For the 10th time in two years, Paul arrived on Monday in Iowa, where the first presidential caucuses will be held in 17 months, to try out his message on a three-day, multi-city, headline-generating tour.

Over the course of the trip, the Democratic National Committee sent out 10 press releases about Paul’s every move and utterance. “What it can tell you as a political observer is that they recognize what we’re trying to point out, which is Rand is the Republican who has the best chance of keeping and energizing the base while going into their constituencies," a senior aide for Paul told The Daily Beast.

Having only run for office the one time, in 2010, Paul is not the most experienced of campaigners—so heading out early seems intended as batting practice. But as the senator is the only likely potential candidate so publicly engaging in this sort of preliminary campaigning, there has been no way for him to practice unnoticed. While he has been testing the waters, the left has been testing its attacks.

Democrats began hitting Paul on Monday morning, first for fundraising with Iowa Rep. Steve King, who has entertained the idea of exploring impeachment (something Paul has said he would not consider); next for claiming he never proposed ending foreign aid to Israel (which he openly supported doing for years); and then for saying Republicans don’t want to ban birth control and that he is “in favor of the concept” of a federal ban on gay marriage.

The most fun the DNC had, understandably, was with an incident that took place at a Monday-night fundraiser with King, when Paul was caught on video getting up—mid-bite into his hamburger—and practically running away from two immigration activists. (He gets an everyman point for taking his drink with him.)

The DNC snarked that the senator’s swift exit was a “profile in courage” and later sent out an email detailing some of the best headlines the moment generated, including “Rand Paul Flees in Terror from Mexican Immigrant,” and “Watch Rand Paul Run for His Life Before Steve King Insults an Immigrant in Iowa.”

A spokesman for the DNC, Michael Czin, made no secret of his glee at Paul’s troubles, tweeting:

Asked if Democrats were intimated by Paul, Czin laughed, “His positions are quite scary.”

“He’s working not to get out of the conservative box but to redefine it,” Simon Rosenberg, president of the New Democrat Network, told The Daily Beast. If Paul gets the nomination, he becomes the effective leader of his party—meaning his redefinition of that conservative box could become the definition, a problem for Democrats, as Paul has a tendency to stake out atypical positions for a conservative and reach across party lines.

Paul has a limited-government, non-interventionist worldview that is particularly attractive after a decade of war, rampant overspending, and privacy invasions.

He has campaigned against domestic spying and the use of drones on American citizens—memorably conducting a 13-hour filibuster in 2013 on the latter—and has criticized both Republicans and Democrats for their foreign policy. He generated headlines this year when he refused to blame recent violence in Iraq on President Obama, instead pointing a finger at the Bush administration, particularly Dick Cheney. In Iowa this week, he labeled the conflict in Libya “Hillary’s war,” providing a preview of what the general election could look like with both of them in it.

And Paul’s determination to make the GOP more inclusive makes him much harder to vilify than conservatives who might stomp their feet at such a notion.

He has made efforts to reach out to black voters that while met with some skepticism (he once questioned the constitutionality of certain parts of the Civil Rights Act) and cynicism have won him supporters and the acknowledgement that he is, at the very least, trying.

In 2013, Paul gave a speech at Howard University that was memorable for all the wrong reasons. Critics slammed him for being condescending and “whitesplaining” by telling his audience about the history of the NAACP and the civil rights movement—not news to students at Howard. But Paul seemed to learn from the incident quickly and continued the outreach. Last month, he traveled to Cincinnati to address the Urban League.

Along with New Jersey Sen. Cory Booker, a Democrat, Paul has introduced a plan to overhaul the criminal justice system with the REDEEM Act. The measure is intended to, in Paul’s words, fix the “cycle of poverty and incarceration” by, among other things, sealing or expunging the criminal records of juveniles. The senators’ partnership has won high-profile fans like musician John Legend.

And policies aside, Paul has the benefit of not being embroiled in any serious scandals—something that cannot be said for many of the other likely Republican nominees. New Jersey Gov. Chris Christie, Texas Gov. Rick Perry, and Wisconsin Gov. Scott Walker are all entangled in scandals of varying degrees of seriousness in their home states. So far, the most damaging thing anyone has uncovered from Paul’s past was his membership in a secret society in college that took part in hijinks like worshipping a satirical deity named Aqua Buddha.

The Democrats’ strategy to defeat Paul seems to be to engage him as he tries to gain experience, with the hope that he’ll misspeak his candidacy to death before it gets off the ground. “This is smart politics for the Democrats,” Rosenberg told The Daily Beast. “What you want to do as opposition is you want to go after the candidates when they’re inexperienced…We saw a deeply inexperienced candidate [in Iowa]...and a lot of early scrutiny could really weaken him.”

Or so the left is hoping.

“It’s kind of dangerous to have a Republican like Rand,” said the senior Paul aide. “It’s blindingly obvious to [Democrats] that Rand is the Republican who can reach across the party.”