The Franklin and Marshall College poll
finds Clinton ahead of Trump 47% to 40% among likely voters, which represents a slight decline from a similar poll taken just after the Democratic National Convention (when she led 49% to 38%).
The new numbers are consistent with another Pennsylvania poll from this week -- a Monmouth University poll released Tuesday found Clinton leading Trump 48% to 40%.
But in a four-way matchup including third-party candidates, Clinton's lead narrows to 41% over Trump's 38%, with Libertarian Gary Johnson at 7% and Green Party nominee Jill Stein at 2%.
The poll also has a much higher share of undecideds than other polls do at this stage, with 13% say they don't know who they would support.
Clinton's favorability has suffered a steep decline from her post-convention bounce. The new poll finds Clinton with a 38% favorable/54% unfavorable rating among registered voters, down from 47% favorable/49% unfavorable in July.
Trump, though, fares slightly worse -- he is viewed favorably by 37% of registered voters in Pennsylvania, compared to 58% who say they have an unfavorable opinion.
According to the poll, Clinton and Trump run about even when voters are asked who will better handle the economy and protect the US from terrorism. But Clinton is viewed as better prepared to be president and better able to handle foreign policy.
Trump is performing well among his key base of support in rust-belt states like Pennsylvania -- he beats Clinton handily among white voters with a high school degree or less, 52% to 35%. But Clinton reverses Trump's advantage among white voters with a college education, leading that group 50% to 29%. And while Trump wins white men, 41% to 38%, that is offset in part by Clinton winning white women by a larger margin, 45% to 38%.
The Franklin and Marshall College poll of Pennsylvania was conducted between August 25 and 29, and surveyed 736 Pennsylvania registered voters and 496 likely voters. It has a margin of error of plus or minus 4.6 points for registered voters, and plus or minus 5.6 points for likely voters.