How do you stop states and cities from forcing more disclosure of so-called dark money in politics? Get the debate to focus on an “average Joe,” not a wealthy person. Find examples of “inconsequential donation amounts.” Point out that naming donors would be a threat to “innocents,” including their children, families and co-workers....

These and other suggestions appear in internal documents from conservative groups that are coaching activists to fight state legislation that would impose more transparency on the secretive nonprofit groups reshaping U.S. campaign finance....

Dark money is the term for funds that flow into politics from nonprofit groups, which can accept donations of any size but, unlike political action committees, are not required by federal law to reveal the identities of their donors. The anonymity has been upheld by courts that cite as precedent a 1958 Supreme Court ruling that the state of Alabama could not demand that the NAACP turn over a list of its members.

Since 2008, dark money groups have spent more than $690 million in federal races, according to the Center for Responsive Politics. A single group aligned with Republican presidential hopeful Marco Rubio helped buoy his standing in Iowa before Monday’s caucuses with$1.3 million in ads.