Due largely to Donald Trump's divisive candidacy, Pennsylvania has shifted slightly to the left, according to Cook Political Report's Electoral Vote scorecard.
Cook, a non-partisan online newsletter that tracks the likelihood of what party states will be won by in a general election, said Thursday it was changing the status of 13 states after Trump became the GOP's presumptive nominee.
Pennsylvania went from "toss-up" to "leans Democratic."
Virginia, Wisconsin, Florida and Colorado saw similar shifts, according to the report. Some changes were more dramatic, as Nebraska's 2nd Congressional District (which can vote separate from the state as a whole) went from "solid Republican" to "toss-up."
Although we remain convinced that Hillary Clinton is very vulnerable and would probably lose to most other Republicans, Donald Trump's historic unpopularity with wide swaths of the electorate - women, millennials, independents and Latinos - make him the initial November underdog.
As a result, we are shifting 13 ratings on our Electoral Vote scorecard, almost all of them favoring Democrats. Our assessments are based on publicly available polling, data on demographic change and private discussions with a large number of pollsters in both parties. Much could change, but undecided voters begin more hostile to Trump than Clinton.
Pennsylvania has not been won by a Republican candidate in a presidential election since 1988. Last month, Trump and Democratic front-runner Hillary Clinton won the state's primaries by large margins.