The intercession of the NRSC into the GOP primary in Florida’s Senate race touched off outrage from conservatives and eventually blew up in John Cornyn’s face when Charlie Crist — the candidate he endorsed — renounced the GOP and went independent.  Perhaps the DSCC, the Democratic counterpart to the NRSC, should have learned a lesson the easy way.  National Journal reports that the committee has spent over $300,000 for Arlen Specter to beat back a primary challenge from Rep. Joe Sestak:

The DSCC is spending a significant amount of money to ensure a former GOP Sen. Arlen Specter (D-PA) wins his May 18 primary, sources with knowledge of the move tell Hotline OnCall.

One source said the DSCC is using coordinated funds to help Specter keep a robust TV presence. Ads that tout Specter’s candidacy now say they are paid for by the DSCC; last week, the disclaimers on the same ads indicated Specter’s campaign had paid for them.

All told, Specter and the DSCC spent about $407K on the joint ad buy last week. A second source said the DSCC’s contribution is about three-quarters of that amount, or around $300K.

Dems backing Specter may be worried that Rep. Joe Sestak (D) is preparing to unleash a slew of late ads in the fortnight before the primary. A new poll released today already shows Specter’s decisive lead is sagging; he leads Sestak by a 47%-39% margin, just 4 weeks after holding a 17-point advantage.

The purpose of these committees is to ensure the election of their party’s nominees to these seats.  However, as the NRSC’s alignment with Crist showed, that can backfire — and badly.  Primary voters resent the Washington establishment’s interference in their business, especially when the primary features another credible alternative.  Plus, in this case, Specter is only a recent convert to the party, and only because of the primary challenge he faced from Republican Pat Toomey.

That switch may have been predicated on precisely this kind of support, however, as these changes almost always get negotiated.  If so, that doesn’t put the DSCC in any better light, and it indicts Senate Democratic leadership with the same brush.  Not only does it make the whole business look like an attempt to marginalize the very Pennsylvania Democrats who will vote in the upcoming election, but it also calls into question their judgment about Specter.  They could have run Sestak instead and saved themselves $300K in the primary, and Specter likely would still have voted for ObamaCare and other Democratic initiatives.

If Specter wins anyway, all the DSCC will have done is to demotivate their voter base in Pennsylvania ahead of the midterm elections, where they already have a serious problem with voter enthusiasm.  If they have to carry Specter across the finish line like this, how can they expect him to beat Toomey in an election where a pro-growth candidate can count on the enthusiasm from Tea Party activists?