A new Bloomberg poll finds Hillary Clinton 9 points ahead of Donald Trump in  the crucial swing state of Pennsylvania — 51 percent to 42 percent among likely voters in a two-way race, and 48 percent to 39 percent, in a four-way race that also includes Libertarian Gary Johnson, who polled at 6 percent, and the Green Party’s Jill Stein, who polled at 4 percent.

Worse for Trump, Hillary is also whooping Trump in the once reliably Republican Philadelphia suburban counties by a 28-point margin in a two-way race, 59 percent to 31 percent. Those four counties accounted for 22 percent of Pennsylvania’s vote in 2012.

According to the Bloomberg Politics article about the poll, Hillary’’s suburban advantage is 18 points larger than President Barack Obama’s winning margin there in 2012. One should take the poll’s Suburban Philadelphia results with a larger grain of salt because the margin of error for suburban voters polled was plus-or-minus 5.1 percent.

Losing Pennsylvania’s 20 Electoral College votes would make it much more difficult for Trump to win the presidency. That is especially so if the Trump campaign is indeed only fighting in four states, including  Pennsylvania after surrendering Virginia:

Both sides have blanketed Pennsylvania with campaign stops and advertising. The state hasn’t backed a Republican for president since 1988 and is second to only Florida in electoral votes among battleground states.

Without Pennsylvania, Trump would still be shy of the 270 electoral votes needed to win even if he won Florida, Ohio, Iowa, and Nevada—all states that voted Democratic in the last two presidential elections—and all the other states fell as they did in 2012.

The Real Clear Politics average for Pennsylvania: Trump vs. Clinton vs. Johnson vs. Stein shows Hillary ahead by 8.7 points. And like the Virginia polling, Trump’s Pennsylvania numbers have been dropping during October.

Trump’s candidacy may hurt the chances for Sen. Pat Toomey to win reelection. The Bloomberg poll finds the Democrat challenger Katie McGinty leading Toomey, 47 percent to 45 percent.

The Bloomberg poll was conducted  October 7-11, and has a  margin of error of  plus-or-minus 3.5 percent. The margin of error for suburban voters polled was plus-or-minus 5.1 percent.