Republican presidential candidates favored by the party establishment have lost ground to Donald Trump since the first GOP debate, according to a new poll, with Jeb Bush, Scott Walker and Marco Rubio all struggling the summer before voting starts.

Former Florida Gov. Jeb Bush has fallen from 15% earlier this month to fourth place among Republican nationally, according to the Fox News survey, with just 9% support. Wisconsin Gov. Scott Walker is tied for fifth place at 6%—down from 9%—and Rubio, the Senator from Florida is in ninth place at 5%. Meanwhile, Trump continues to dominate the GOP field nationally, with the support of 25% of Republicans.

The poll does not necessarily reflect the preferences of likely Republican voters and caucusgoers in the key early-voting states of Iowa and New Hampshire, but recent surveys have found Trump leading there, too. Republicans have been flummoxed by Trump’s seeming invincibility even in the wake of incendiary—and often widely-condemned—comments.

Other anti-establishment candidates, including retired neurosurgeon Ben Carson and Texas Sen. Ted Cruz, have also risen, capturing 12% and 10% in the Fox News poll, respectively.

The survey of 1,008 registered voters, conducted Aug. 11-13, has a margin of error of plus or minus three percentage points.

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