Fair political polling is a statistical balancing act
Poll: Clinton's lead shrinks in Pennsylvania
A Monmouth University survey of Pennsylvania - a traditionally blue state that Trump hopes to flip - finds Clinton taking 48 percent support and Trump taking 44 percent, a difference that is within the poll's 4.9 percentage point margin of error.
That's a significant narrowing from the same survey in October, which found Clinton leading 50 percent to 40 percent.
A CNN-ORC poll released Wednesday also found Clinton leading 48 to 44 in Pennsylvania.
The Monmouth survey was conducted after the FBI announced a new review of emails connected to the private email server Clinton used as secretary of State.
"Clinton is still in the lead, but the race has tightened in the past four weeks," said Monmouth pollster Patrick Murray. "It looks like this shift was in the works even before Friday's FBI bombshell, which has made only a small contribution to this overall narrowing."
Eighty-nine percent of voters said the news about the FBI investigation did not influence their decision at all. Overall, the news likely only provoked about a 1 point shift in favor of Trump, Murray said.
Rather, Trump's gains are largely due to his growing support among white women. He still trails Clinton among the group, 45 percent to 48 percent, but has gained considerable ground over the last survey, when he trailed among white women 35 percent to 55 percent
In addition, Clinton's favorability rating has ticked down from a net negative of 7 points in October, to a net negative of 17 points.
She still fares better than Trump on favorability, but his rating has gone from 33 points under water in October to 22 points down in the latest poll.
In the Senate race, Democrat Katie McGinty leads incumbent GOP Sen. Pat Toomey 47 to 44, according to the poll, with 3 percent saying they support the Libertarian candidate. The race was tied at 46 percent in the same poll last month.
The Monmouth University survey of 403 likely voters in Pennsylvania was conducted between Oct. 29 and Nov. 1 and has a 4.9 percentage point margin of error.