Donald Trump is and has been the Republican 2016 front-runner for quite some time now. The Republican establishment continues to struggle with that fact, but the reality is that Trump could absolutely be the GOP presidential nominee.

Trump has led the Republican race — as measured by the average of national polling — for the vast majority of the past four months, a run that eclipses any other GOP candidate in the contest this year. Think about that for a minute. Trump, who didn't announce his campaign until mid-June, has led the race for the longest time of any of the 18 (or so) candidates who have run or are running for the GOP nod.

This chart, built by the Fix's Philip Bump, compares Trump's time as national front-runner to his rivals, as well as to Hillary Clinton's run as front-runner on the Democratic side.

See that brief break in Trump's dark red line right around day 100? That was the Ben Carson moment — when the retired pediatric neurosurgeon passed Trump nationally (and in Iowa.) I use the word "moment" purposely; Carson's lead lasted roughly one moment before Trump not only retook the top spot but also widened his edge over the field to a margin not seen since day 75 (or so) of his time at the top.

So, not only has Trump led the GOP race for more days in 2015 than any other candidate, but he has also taken a polling punch from Carson and bounced back stronger than he was before it.

That's durability and resilience.

None of that means that Trump will be the Republican nominee when the summer of 2016 rolls around. But what it does mean is that the time for the Republican establishment to sit and hope that he  fades away has passed.

The question for those who fret that Trump could bring down the entire Republican Party with him if he is the nominee is: Now what?