Senator Rand Paul announced today (to absolutely nobody's surprise) that he is running for the Republican presidential nomination for 2016. He joins only one other official candidate, Senator Ted Cruz, who made his own announcement a few weeks ago. On the Democratic side, nobody has officially thrown their hat in the ring. Such announcements are happening much later this presidential cycle, due to quirky financial advantages of our crazy campaign finance legal system (if it can even be called that, anymore, after the Supreme Court's evisceration). But I'm getting distracted, and veering off the topic at hand, which is paying proper attention to those candidates who actually are declared candidates. Since nobody else has officially stepped up to the podium yet, Ted Cruz and Rand Paul deserve at least a moment in the spotlight.

This period may not last long -- the rumors are that Marco Rubio is about to announce, and that Hillary Clinton won't be far behind. Sooner or later, the floodgates will open wide on the Republican side and we'll have more candidates than you can shake a stick at, but for now we only have these two to examine.

Both Ted Cruz and Rand Paul are going to have a big impact on the 2016 Republican nomination contest, in different ways. Neither is a bland or milquetoast candidate, obscurely languishing in the shadows of the Republican pack. Both men are unpredictable to a degree, in terms of what they'll say on any given subject. Both have the potential of really shaking the race up and forcing their Republican opponents to respond to their positions. But that's about where the similarities end.

Since he announced first, let's first take a look at Ted Cruz. Cruz is running as (if I may coin a term) an "insider/outsider." He really wants to run an "outsider" candidacy, running hard against "Washington," but this is not technically possible since he is a sitting member of the United States Senate. It's hard to be all outsider-ey when you're that far inside, in other words.

Cruz is a first-term senator from Texas, and in the two years he's been in the Senate so far, he has certainly made much more of a name for himself than the usual freshman senator manages. His problem is that he's made this name for himself at the expense of his party's caucus. Cruz is best known as a bomb-thrower (in the finest Newt Gingrichian tradition) who values political stunts and political theater over actually getting anything done. His most famous moment might be his "non-filibuster filibuster," where he read Green Eggs And Ham on the floor of the Senate, while totally ignoring the simplistic childhood moral contained within the book ("try new things, you might be pleasantly surprised," while Cruz was holding the budget hostage in an effort to kill a new program, Obamacare).

To put it bluntly, other Republicans are scared of Ted Cruz, and scared of what he represents. His supporters would likely cheerfully accept that analysis, and perhaps add "because he represents the Tea Party." But that's not exactly what scares some Republicans about Cruz. Instead, it is the "style over substance" part that truly worries them. Cruz led both the House and the Senate into a government shutdown, and then did a fine example of "the dog who caught a car and didn't know what to do with it." He had no exit strategy whatsoever. He had no path to success or even partial victory mapped out, other than "and then Obama gives us everything we want." Even worse, he had no "Plan B" for what to do when his main effort failed -- as it was doomed to. Cruz was happy enough just picking a big political fight, and he sure had fun fighting it, but he had never once considered how it would end -- whether good, bad, or indifferent. So he essentially just walked away from the wreckage, and let others clean it up.

That's not exactly behavior to endear you to your fellow caucus-mates. Which is why every other Republican presidential candidate is already terrified of Ted Cruz. They already know Cruz is going to stake out some radical and extreme positions, and then turn around and challenge all the other Republicans running to prove their purity or face the Tea Party's wrath and scorn. All his competitors know that Cruz doesn't really care whether he's got an answer to any problem or not -- because he gets more fun out of ranting and railing about the problem. Republicans who have an actual shot at winning a general election campaign know full well that Cruz isn't even all that concerned with winning or losing the White House, as long as he has fun on the campaign trail. Which makes Cruz very dangerous for all the other Republicans. One way or another, though, Cruz will indeed have an influence on the nomination race. Either other Republicans will make news by breaking with Cruz on a particular stance, or they will make news by jumping on board. Both will come with risks, obviously.

Which brings us to Rand Paul. Paul is also an interesting character under the Republican tent, but in Paul's case it doesn't stem from uber-orthodoxy but rather from challenging entrenched Republican dogma. Paul, like his father, comes from a Libertarian background. But Rand, unlike Ron, has managed to move pretty far away from a pure Libertarian stance, and as 2016 gets closer and closer has been willing to change his positions to more closely resemble traditional Republican ideas, especially on foreign policy. Rand Paul will be making a campaign speech soon in front of the USS Yorktown, an aircraft carrier. That's an enormous sea-change, right there, to use a nautical term.

What all this means is that Rand Paul might be less willing to go against the traditional Republican grain as you might think, especially since he seems to have a much better shot at gaining wide support among Republican primary voters than his father ever did. But he won't be able to disassociate himself fully with his previously-held beliefs, as all the other Republicans in the race will be there to helpfully remind him. Whether he wants to or not, he's going to have to address his unorthodoxy on a few debate stages later this year, to put this another way.

But this has always been Rand Paul's value to the Republican Party. He has been willing to challenge old Republican concepts, and he has been willing to consider new ideas. That alone separates him from a large part of the Republican pack. But, unlike with Ted Cruz, his fellow Republicans in the nomination race do not fear Paul or his positions at all. Rand Paul is going to become the favorite foil (or punching bag, choose your metaphor) for the rest of the Republican candidates. This is already on display -- last Sunday, Lindsey Graham was interviewed about President Obama's deal with Iran, and Graham said something along the lines of: "It's probably the best deal this president could have gotten, but any Republican president -- except for Rand Paul, of course -- could have gotten a better deal if he were president." Graham is not an announced presidential candidate, but is rumored to be seriously considering a run.

Rand Paul and Ted Cruz can be seen as occupying two very different poles of influence in the Republican presidential race. Cruz will be staking out the most belligerent and radical positions possible, if he runs true to form. He will be challenging other Republicans to equal his fervor on whatever issue-of-the-week the media is obsessing over, and decrying those who don't. Other candidates will not be able to ignore him, whether they wind up agreeing or disagreeing with him. Rand Paul will be trying to draw the entire Republican Party in a different and new direction, which will likely earn him nothing but scorn from the more extreme candidates running. However, one thing Paul has going for him is that he is sounding an alarm within the party over their increasingly-dismal demographic position. Paul is attempting to champion issues that he thinks will attract younger and more diverse voters to his party. Younger and more diverse voters may not actually agree with much of what Paul stands for, but this is really immaterial to the struggle going on within the Republican Party. The more mainstream and establishment Republicans know full well that Paul's got a point -- they've been worrying over the same demographic trends themselves. So candidates with an eye on actually winning (concerned with the general election and not just the primaries, in other words) may pay more attention to Paul's positions than you might think. Once again, it's a pretty safe bet that the other Republican candidates won't be able to ignore Rand Paul, one way or the other.

Which defines both men as influential within the Republican nomination race. Does either of them have a chance of winning their party's nomination? Perhaps, and perhaps not. It's way too early to judge, really. But neither Ted Cruz nor Rand Paul can be dismissed as any sort of lightweight or meaningless candidate. The very fact that each is going to have a definite influence on the primary election season is reason enough to take them and their candidacies seriously.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant