Look at it this way. Picture yourself as a liberal Democratic PA primary voter. Here are the words that stand out in this call associated with each candidate:

Joe Sestak: for President Obama's budget, Democratic priorities, housing and environmental protection, Obama agenda

Arlen Specter: new Democratic senator, stood with conservative Senate Republicans, opposing the Obama budget

If I'm a Democratic primary voter (and I am), all of this will just make me more inclined towards Sestak, and less towards Specter. And the fact that the GOP is ostensibly vouching for Specter will just make me distrust him that much more.

Which is exactly the point: Hurt Specter's standing with Democratic base voters so that Joe Sestak emerges as the nominee (and more power to them).

If the NRSC were really trying to make Sestak less popular, wouldn't they slap him with terms like "big government" or "energy tax" or "taxes for tuition benefits for illegal immigrants who come here to study abortion"? Do they really think "environmental protection" is a turn-off for Democratic primary voters and opposing Obama is a turn-on? They may be tone deaf, but not that tone deaf.