Donald Trump. Jessica Kourkounis/Getty Images The only major national poll that consistently showed Donald Trump ahead of Hillary Clinton has, with the wave of polls swinging dramatically in favor of the Democratic nominee, also shifted in her favor.

On Wednesday, Trump trailed Clinton in the Los Angeles Times/University of Southern California poll by 0.4 points. It was the first time he was behind in the poll since September 11 — ending a monthlong stretch in front in the head-to-head matchup.

The poll skews more favorably for Trump because it relies on past voting preferences, which experts say is a potentially perilous method of sampling because of voters' tendency to misreport whom they've voted for in the past.

Trump's support has collapsed after Friday's shocking revelations from a leaked tape, in which he boasted he could "grab" women "by the p---y" because "when you're a star, they let you do it."

Clinton has gained nearly 2 points on Trump in the RealClearPolitics average of several polls since the 2005 tape surfaced. She leads by an average of 6.2 points in the head-to-head battle.

Other polls released Wednesday found that Trump is well behind Clinton in the key swing state of Ohio and tied in Utah, a state that has traditionally voted for Republican presidential candidates.