Trump's net favorables are up 16 percentage points in the last two weeks; Bush is down 6.
Another poll found Sanders pulling within 7 points of Clinton.
His lead over the Republican primary field is growing.
Forty-five percent said they consider her use of a private email server a "serious scandal."
Forty-nine percent of all voters also believe Trump will be the nominee.
A Republican hasn’t won the state in a presidential election since 1984.
PPP poll finds eight Republicans beating her in head-to-head contests in the swing state.
A majority also think the private email server endangered national security.
Walker, who led for months, is on the decline, with Carson surging to second.
Julian Hattem 07/27/15 09:18 AM EDT
Most voters support the Iran deal, according to the poll.