A conservative group spent $1 million last election year as it helped boost Republicans into the majority in the state Legislature.
Go West Virginia Inc. revealed the totals in a 2014 tax filing, but didn't disclose donors.
The nonprofit bought advertisements bashing Democrats, which helped Republicans clinch their first legislative majorities in more than eight decades.
Go West Virginia gave $355,000 to another ad-buying conservative group, Grow West Virginia, which does disclose donations. The U.S. Chamber of Commerce Institute for Legal Reform gave Grow West Virginia $500,000.
Go West Virginia held a $25,000-per-plate January fundraiser. The nonprofit canceled a $100,000-per-plate fundraising breakfast in March after media outlets reported on it.
Honest West Virginians, a union-funded group, spent almost $1.4 million as the top outside spender for state Democrats last cycle.