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Donald Trump is now the Republican Party’s establishment-lane candidate

What Donald Trump is doing on the campaign trail

U.S. Republican presidential nominee Donald Trump speaks at a campaign event at Trump Doral golf course in Miami, Florida, U.S. July 27, 2016. REUTERS/Carlo Allegri (Carlo Allegri/Reuters)

If you look at past polling, we've reached the stage of the year where past presidential primary winners had largely already been identified. On Feb. 17, 2004, John Kerry held a huge lead among Democrats that he'd keep. In 2008, Barack Obama and John McCain each led his party on this day, and would keep on leading until their conventions. The year 2012 is the only exception, with Rick Santorum having seized the GOP lead from Mitt Romney -- and Romney seizing it back two weeks later, for good.

In each of those years, we had more primary elections under our belts than we do now, but, with the exception of the 2008 Democrats, we also had less stability. Donald Trump will have led in Real Clear Politics' polling average nationally, save a day or two when he was tied with Ben Carson, for precisely seven months this Saturday -- the day he is likely to win South Carolina's Republican primary on a perhaps-unstoppable run to the nomination.

Donald Trump's feud with Jeb Bush just keeps getting more heated. (Video: Peter Stevenson/The Washington Post)

How'd he do that? Weirdly enough, by becoming the choice of the Republican center -- the group that was supposed to be trying to pick among Jeb Bush, Wisconsin Gov. Scott Walker and New Jersey Gov. Chris Christie right about now.

A new poll from Quinnipiac University shows how the field has evolved since December, back when there were 14 Republicans to ask about, not six. Trump jumped from 28 percent support to 39 percent, essentially absorbing the equivalent support of those eight candidates who dropped out. (Those eight totaled 12 percent of support in December.)

This increase came despite Trump still being the candidate who the largest number of Republicans find unacceptable. Two-thirds of Republicans either plan to vote for him or refuse to do so. For the other candidates, at most a third have an opinion one way or the other.

Sen. Ted Cruz (Tex.), as you'd expect, seizes the most support from very conservative voters, as he has since December. But Trump holds the support of somewhat conservative and moderate voters by a much wider margin, and he has gained significant support since December.

Interestingly, while Cruz leads among tea party supporters -- a group that overlaps heavily with that very conservative group -- Trump holds a slight lead with evangelicals. Suggesting, as we're seeing in South Carolina polling, that the overlap between conservatives and evangelicals isn't as uniform as it once was.

When Christie, Carly Fiorina and all those others dropped out, the long-term beneficiary appears to have been Trump, the candidate who has locked down that less strident wing of the Republican Party to which Bush once aspired.

Here are some of the most memorable campaign promises Republican presidential candidate Donald Trump has made in seven months on the trail. (Video: Sarah Parnass/The Washington Post, Photo: AARON P. BERNSTEIN/The Washington Post)

Again, we're still relatively early in this thing, compared with years past. But since 2004, there have not really been any shocking reversals of direction after mid-February. Not that Republicans are complaining.