Rand Paul announced his candidacy for the Republican presidential nomination in Louisville Tuesday. He began, “I have a message – a message that is loud and clear and does not mince words: We have come to take our country back.” While his supporters cheered his announcement, several questions remain for Paul, not least of which is whether a libertarian can earn the support of enough Republicans to win the nomination in a field soon to be crowded with other highly attractive candidates.

Dr. Paul certainly seems to be a fine man. He’s a church-going Christian with a wife and three sons. He’s an ophthalmologist who often extends his services free of charge to those who can’t afford them. Through the Children of the Americas Program, he provides these services to children throughout Latin America.

Paul is a great asset in the Senate, to which he was elected during a swell of Tea Party enthusiasm in 2010. He’ll simultaneously run for re-election in 2016 after Kentucky’s legislature made a special exception for him to seek two offices, normally not allowed by law.

But Paul has virtually been a presidential candidate since he was first elected, and that has made for some unconvincing policy shifts – especially on national security – as he tries to position himself for electoral success. For example, he raised a few eyebrows with the rapid evolution in his foreign policy views, leaving many to wonder whether he really knows what foreign policies he would pursue as president.

Recently, he called for an increase of $76 billion in defense funding, raising the Senate Budget Committee’s total to $696 billion. (Interestingly, Marco Rubio has called for the same increase.) But in 2011, his first year in the Senate, Paul proposed significant cuts in defense spending. The change is almost certainly driven by primary politics.

And last year, Paul’s opinion regarding airstrikes against ISIL evolved from “very skeptical” to strongly supportive in a three-month period. Whatever the merits of the issue, any Republican candidate would be grilled about such a sudden change in opinion regarding a critical foreign policy.

Needless to say, his voting to raise the defense budget won him no plaudits among libertarians. “[L]et’s be clear: It ain’t gonna help at all with libertarians who see in Paul their best hope for a major party politician whom they would vote for in a presidential race,” wrote Nick Gillespie, editor in chief of the libertarian Reason.com. “Paul toys with lower-case libertarians at his own peril.”

Still, Paul hopes he can build a coalition of fed-up conservatives and Millennials large enough to win.

Paul’s social agenda includes transforming our criminal justice system, which currently imprisons people for relatively minor offenses, putting them into penitentiaries where they learn how to be hardened criminals. Instead, Paul says petty criminals could be forced to make restitution, and mandatory minimum sentencing should end.

As American Spectator editor R. Emmett Tyrell explains, “The United States has less than 5 percent of the world’s population, but it has 25 percent of the world’s prisoners. According to the Charles Koch Institute, incarceration leads to ‘a 40 percent decrease in annual earnings, reduced job tenure, and higher unemployment.’”

In his speech Tuesday, Paul said he wants to see a new economic boom and “a return to a government restrained by the Constitution.” The two are related. “Opportunity and hope are slipping away for our sons and daughters,” he warned “[a]s our once-great economy collapses under mounting spending and debt.”

“Congress will never balance the budget unless you force them to,” he added. “I propose something extraordinary. Let’s just spend what comes in.”

Furthermore, he said, “Under the watch of both parties, the poor seem to get poorer, the rich get richer. … My plan includes economic freedom zones to allow impoverished areas to prosper … by leaving more money in the pockets of the people who live there.”

He spoke without benefit of a teleprompter, something all prospective Republican candidates do well. He offers many good ideas that could reignite both the economy and the flame of Liberty. He just has to win the primaries.

At least two people present a clear challenge to Paul on that front. The first is fellow candidate Ted Cruz, who is a maverick of a somewhat similar ilk and will compete for Tea Party votes. Cruz called Paul his “good friend,” but the two differ on important issues, the major one being the extent to which America should extend herself in the world militarily.

The second man who could undermine Paul’s run is his father, Ron Paul. The elder Paul doesn’t share the nuanced views of his son and likes to call ‘em as he sees 'em – which is sometimes alarming to conservatives. It’s hardly likely that he’ll remain silent throughout the entire campaign. “Pop” could end up being the shot that ends Rand’s campaign.

In short, Paul’s announcement is just the second in what is sure to be a long string of candidates. Indeed, 2016 will present the most wide-open field the GOP has seen in a very long time, and we expect a spirited campaign.