Nate Silver says so:
Finally, in Pennsylvania, Republicans were in need of a strong candidate to seriously challenge the Democratic incumbent, Bob Casey, who is fairly popular. Instead, their field failed to coalesce and they picked an inexperienced nominee, the businessman Tom Smith, in their primary in April. We classify the race as Safe Democrat, rather than Likely Democrat as before.
I don’t plan to write about this race much. Tom Smith’s been reduced to running ads about boring budget process issues that nobody cares about.
Note, however, that this means Casey shouldn’t be breaking with the Democrats on anything for the rest of the year.