The Institute on State Money in Politics has released this report. Here is how the executive summary begins:

State political parties have increasingly taken on a more active — yet less visible — role of supporting the activities and agendas of their national counterparts, serving as a conduit and clearinghouse for millions of dollars in contributions. And if history is a harbinger of things to come, state party committees could be pivotal to the flow of money into the federal political system in the future, whether the Bipartisan Campaign Reform Act (BCRA) survives legal challenges or not.
While the BCRA ban on soft money closes one fund-raising door at the federal level, 50 other doors remain wide open in the states. Those doors lead to a financial arena governed by 50 different sets of laws and regulations, many of which are as loose as the federal campaign-finance law was before BCRA.
A 13-state study by the Institute on Money in State Politics details the financial impact state party committees may feel should the federal soft-money loophole remain closed. The Institute examined the soft money raised and spent by state-level party committees in the 1998, 2000 and 2002 election cycles and documented ways in which the state parties have been used to circumvent federal spending regulations.
The study found that 61 state and legislative party committees raised $917.5 million in soft money over the six-year period. The six national Republican and Democratic party committees funneled more than $280 million in “soft money” into state-party activities, representing 30 percent of the money these committees raised. Under BCRA, national committees are now prohibited from raising those funds. The study found that two activities in particular — transfers and trades — allowed the national parties to conserve or gain “hard money,” the funds that are raised under federal contribution limits and can be used for any purpose, including supporting federal candidates. Soft money, raised outside the limits, could only be used for party-building activities, including so-called issue advertisements that don’t directly support or oppose a candidate.

The A.P. offers this report on the study.