Trump enters debate week in dominant position

All of the previous assumptions about Donald Trump and his possible GOP support are discredited. His position at this point is now unexpectedly dominant.

Donald Trump greets supporters, tourists and the curious after taping an interview with Anderson Cooper at a Trump owned building in mid-town Manhattan on July 22, 2015 in New York City. 
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Many campaign observers, including me, assumed Donald Trump had reached a poll ceiling of sorts. The Republican presidential hopeful, who was in the low single digits as recently as April in national polling, has obviously rocketed to the top of the field, but many of us saw his relatively modest advantages as fleeting. It's not like he was crushing his rivals.
 
But those assumptions are due for an overhaul. As Republicans get ready for their first debate, Trump's position in national polling is, in fact, dominant. Here's the latest Fox News poll released last night:

Businessman Donald Trump continues to gain ground in the race for the Republican nomination.  What's more, the number of GOP primary voters saying they would at least consider backing Trump has more than doubled in the last two months. [...] Trump receives the backing of 26 percent of self-identified Republican primary voters -- up from 18 percent in mid-July and 11 percent a month ago. That's not only the highest level of support for Trump, but it's also the highest any GOP candidate has received since the Fox poll began asking the question in December 2013.

Jeb Bush is second in the poll with 15%, followed by Scott Walker at 9%. Do the math -- Bush's and Walker's support combined falls short of Trump's backing in this poll.
 
This morning, a new Bloomberg Politics national poll also showed Trump with a significant lead over his GOP rivals. The former reality-show host leads with 21%, followed by 10% for Bush and 8% for Walker. Yes, that means another poll in which Trump tops the combined support for his next two closest rivals. (Yesterday's Monmouth poll also found Trump leading Bush and Walker combined.)
 
In the largest primary field in American history -- 17 Republicans are competing for their party's nomination -- it's tough for any candidate to enjoy support from a significant chunk of the GOP, but on average, Trump has the backing of roughly a fourth of Republican voters.
 
No candidate has put up numbers like these all year.
 
All of the assumptions, some of which I'd bought into, about Trump's appeal being limited to fringe elements are suddenly much harder to believe -- that is, unless one is comfortable characterizing much of the Republican base as "fringe."
 
It's gotten to the point at which Trump is appealing to voters who shouldn't even give him a second look. Bloomberg's Josh Green noted this morning that Trump, despite being a thrice-married candidate who's never shown much public interest in religion, is even leading among self-identified "born again" Christians.
 
All of the usual caveats apply, of course. It's still early; we can think of other candidates who've lost summer leads before the primaries; Trump's an undisciplined campaigner who might implode at a moment's notice; etc.
 
But at least for now, Republicans are buying whatever Trump's selling. All of the Beltway pundits who assumed his support would evaporate after his recent criticism of John McCain had it backwards.