Both major parties’ congressional campaign units make a practice of setting up joint fundraising committees. These operations share the contributions they receive between the national party organization and individual candidates who are up for election in the current cycle.

But a Democratic fundraiser held in June, from which the Democratic Senatorial Campaign Committee (DSCC) netted the lion’s share of the proceeds, highlights the fact that having a joint committee usually does not mean a 50-50 split.

The event on June 15 event at the Ritz-Carlton Hotel in Chicago, was headlined by White House Chief of Staff Rahm Emanuel, a former House Democrat from Illinois. And it raised more than $600,000 for “Senate Victory 2010.”