Bills advancing through the Legislature would give California's campaign watchdog agency more power and require political nonprofits to reveal their donors.

Democratic lawmakers in the Assembly and Senate passed the legislation Thursday over Republican opposition.

The proposals respond to $15 million in anonymous donations that were funneled through conservative groups to influence two 2012 initiative campaigns.

The Senate bill requires tax-exempt nonprofits involved in politics to report donors.

It also requires campaign committees that raise more than $1 million to maintain a list of their top 10 donors. 

The Assembly bill gives the Fair Political Practices Commission greater enforcement authority and the ability to audit campaign funds before elections.

Both return to their original houses for votes on amendments. If signed into law, they will be in effect in time for the November elections.