The government watchdog group Wisconsin Democracy Campaign released the report on Thursday. It found that incumbents hold an 8-to-1 cash advantage over challengers in money raised through June.
The report says the $3.98 million raised is the most for the first six months of an election year, but falls short of the $6.8 million that came in for nine Senate recall elections in 2011.
Republicans are doing better than Democrats in raising money. The report says the 136 Republican candidates on the ballot raised about $2.3 million, roughly 35 percent more than the $1.7 million raised by 105 Democratic candidates.