Pat Toomey and Rob Portman are a lot alike.

They both represent neighboring swing states in the Senate. They are both fiscal conservatives with long careers in government. Finally, they were both elected to the Senate in 2010 and thus face their re-election battles this year.

Despite all that, though, Rob Portman is pulling ahead while Pat Toomey falls behind.

Why is this? Both incumbents are spending enough money and neither of their opponents have run error free campaigns.

You may believe that the disparity is the result of Donald Trump dragging down the ticket but that’s only half the answer. The other half concerns those that are being alienated by the GOP presidential nominee, namely whites with a college degree.

As others have noted, this demographic has traditionally gone Republican but appears ready to turn blue for the first time in the polling era.

To understand why this makes such a difference you have to know about the demographic differences between Ohio and Pennsylvania. For instance, Ohio has more black voters although PA has more Hispanics. The key factor, though, is education.

Check out this chart from the Cook Political Report:

Pennsylvania has significantly more college educated whites than Ohio does. As a result, according to the RealClearPolitics average, Clinton’s lead in the Keystone State is 9.2% while her advantage in the Buckeye State is just 4.8%.

In that context, the fact that Toomey trails by 2.6 points while Portman leads by 6.4 makes sense.

Ultimately, Sen. Toomey will have to target the college educated voters in PA’s Acela corridor in order to win his second term.