CUNA's Credit Union Legislative Action Council raised $4.3 million and spent $4.3 million during the 2007-2008 cycle, and it still had $393,527 left in its coffers.
NAFCU-PAC raised $458,522 and spent $419,573 and had $151,486 left.
Both groups recently filed their annual reports with the Federal Election Commission.
CULAC, which is the 13th largest PAC in terms of contributions, donated $2.2 million to federal candidates and committees, 54% to Democrats and 46% to Republicans.
It contributed $1 million to Democratic House candidates and $847,289 to GOP House candidates. CULAC also gave $169,100 to Republican Senate candidates and $119,500 to Democratic Senate candidates.
NAFCU-PAC donated $346,857, 63% to Democrats and 37% to Republicans.
It contributed $161,211 to House Democratic candidates and $91,226 to GOP House candidates, and $18,500 to Senate Democratic candidates and $16,500 to GOP Senate candidates.
PACs from the credit union industry gave a total of $2.7 million to federal candidates and committees, 55% to Democrats and 45% to Republicans, according to data compiled for the Center for Responsive Politics.
After CUNA and NAFCU, the biggest credit union PACs are Orange County Teachers Federal Credit Union ($42,900), managed by recently renamed SchoolsFirst FCU; U.S. Central Corporate Federal Credit Union ($38,310), Wescom Credit Union ($31,850), CUNA Mutual Insurance Society ($29,350) and Affinity Federal Credit Union ($17,437).