A Political story discusses the large number of Pennsylvania voters switching party registration from Republican to Democrat:

That statewide Democratic surge has been accompanied by a flood of party-switching. More than 178,000 voters have changed their party status since January -- and the Democrats have captured 92 percent of those voters.
. . .
Those party-switchers now represent about 7 percent of the roughly 2 million Democratic voters expected to turnout Tuesday, said [Terry] Madonna.

Which candidate does this help? The Politico analysis infers the switching is concentrated in areas that benefit Obama:

For instance, about 143,400 Democratic newcomers - including newly registered and party switchers -- are in Philadelphia and its suburbs. Those numbers could help Obama rack up big margins in what is considered his strongest turf.

About 28,400 of them are in or around Pittsburgh, an urban area Clinton needs to counter Obama's Philly support. Another 30,000 of them hail from the generally smaller, conservative counties in the state's northwest and southwest, a region that Clinton is hoping to draw Reagan Democrats back to the party and to her cause.

There's also a poll of these switchers which purports to give Obama the edge:

A poll [Franklin & Marshall College Poll] of those switchers and new registrants released by Madonna last week found that Obama was the preferred candidate for 62 percent of them. Clinton insiders said they are also bracing for the same 60-40 split among newly registered Democrats.

I'm not going to put much weight on either of these indicators. I think this is a hard phenomenon to measure and thus I'll wait for the exit polling to sort it out.

It's been amusing listening to comedian Rush Limbaugh puff himself up for weeks with his so-called "Operation Chaos," wherein he directs listeners to cross over and vote for Senator Clinton. One wonders how he can credibly claim to be influencing the Democratic primaries, when he obviously had very little impact in his own party's primaries. Perhaps that's the point--to mask his earlier failed effort to shape the election.