The defining issue of the 2016 Republican primary -- the issue that divides the winners from the losers, the survivors from the political roadkill -- has probably been immigration. The two frontrunners, Ted Cruz and Donald Trump, take an uncompromising approach to the issue, refusing to even consider offering legal status to those here illegally. And one by one, those candidates who took a less absolute position have fallen by the wayside.

The major exception would seem to be Marco Rubio, but even his campaign is faltering and may not survive another week. He has never quite recovered from his involvement in the so-called Gang of Eight attempt at comprehensive immigration reform, and because of that history is considered by many conservatives to be a traitor to the cause, and at best too weak to be trusted.

But let's take a look at what exit polls are telling us:

A majority of Georgia Republican primary voters -- 53 percent -- believe that those immigrants working here illegally should be offered a pathway to legal status. Just 39 percent believe that those here illegally should be deported to their home country.

Again, this is in Georgia. More to the point, this is among Republican primary voters in Georgia. But is that an outlier of some sort, an artifact of polling?

No. Quite the contrary.

The results were similar in neighboring South Carolina. Among Republican primary voters in the Palmetto State, 53 percent believe that illegal immigrants should be granted legal status. Just 44 percent believe that they ought to be deported.

In Tennessee, the numbers were 49-44 percent in favor of legal status. In Arkansas it was 47-44 percent. In Texas it was 47-43; in Oklahoma it was 50-47. The only Southern state to break the trend was Alabama, and even there it was 45 percent in favor of legal status, and 50 percent in favor of deportation, which is hardly a monolithic rejection of so-called amnesty.

In northern states, the results were even more lopsided. In New Hampshire, for example, 56 percent of Republican primary voters supported legalization, while 41 percent backed mass deportation.

So how does a position held by a minority of Republican voters even in the most conservative areas of the country become THE litmus test for viability among Republican presidential candidates? How does a minority in one party wield so much influence that it can effectively shut down any progress on an important issue at the national level?

There are many ways to answer such questions, but in the end, it comes down to the unwillingness or inability of Republican leadership to challenge their own extremists, to the detriment of their party and country. And if you give extremists that power over you, you in time become defined by those extremists.