Series: The Breakdown How politics and government really work, and why they don’t.

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.

And never call it dark money. “Private giving” sounds better.

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.

The documents obtained by ProPublica were prepared by the State Policy Network, which helps conservative think tanks in 50 states supply legislators with research friendly to their causes, and the Conservative Action Project (CAP), a Washington policy group founded by Edwin Meese, a Reagan-era attorney general.

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.

The same story is playing out on the state level. During the 2014 election cycle, 40 nonprofits spent $25 million on TV ads about state races, according to an analysis by the Center for Public Integrity. That represented 3 percent of total ad buys, almost double the proportion that dark money paid for in 2010.

This year, 38 states are considering bills relating to disclosure, according to a database compiled by the National Conference of State Legislatures. Some have already adopted rules. In 2014, California began requiring nonprofits that engage in campaign activity to live by many of the same disclosure regulations as traditional political committees. Montana decided last year that politically active nonprofits would have to disclose donors, and report any electioneering communications within 60 days of votes being cast.

A memo distributed by CAP in January to conservative activists highlighted new disclosure rules being considered in Minnesota, Missouri, New Mexico, Pennsylvania, Tennessee, and Washington, as well as ethics bills in South Carolina and Texas that contain disclosure provisions.

Groups that are throwing their resources behind stricter campaign finance regulation include Common Cause, which has offices in 36 states, and the Democracy Alliance, an invitation-only organization composed of wealthy liberal donors. According to CAP, though, the initiatives to require disclosure not only pose a threat to free speech but also to the very existence of the nonprofits.

A flyer distributed to members of the State Policy Network, which helps conservative think tanks in 50 states supply legislators with research friendly to their causes.

“This well-coordinated, well-funded effort to require conservative nonprofits like yours to divulge the names and addresses of your donors is all part of a plan to choke off our air supply of funding,” the group said in the memo.

The memo was signed by many leading voices on the political right, including anti-tax advocate Grover Norquist; top officials at Americans for Prosperity, an advocacy group backed by the Koch brothers political network; the Family Research Council; the Council for National Policy; and Heritage Action for America. It describes conservatives as “a persecuted class” and compares labeling private donations “dark money” to calling private ballots “dark voting.”

The State Policy Network, which on its website calls pro-regulation activists "enemies of debate," distributed its documents at a conference held last fall in Grand Rapids, Michigan. The material includes a map of cities and states considering measures to “force disclosure of charitable giving” and a set of “questions that help people see the consequences of public disclosure.” Among them: “Do you think the government should be able to take down names and addresses of Americans and who they donate to? Do you think people should be targeted for expressing their opinions?”

The organization also urges its supporters to choose the right phrases to color the debate, shunning terms such as “activist,” “anonymous” or “dark money” in favor of “private giving,” “censor” and “silencing dissent.” Under the header “Framing the Issue,” a man is pictured with tape over his mouth.

Other documents give conservative activists tips on where to look for “efforts to stifle free speech,” for example in bills that deal with corruption or ethics, or that define electoral activity. “More than a dozen states have considered or passed legislation that changes the definition of electioneering communications to include the everyday activity of non-profit groups, like issuing a non-partisan voter guide,” one briefing says.

Meredith Turney, a spokeswoman for the State Policy Network, said in an interview that along with the materials provided to members, the organization is alerting nonprofits regardless of political orientation that the proposals would interfere with privacy and free speech.

“These laws will impact groups from Planned Parenthood to The Heritage Foundation and start-up movements like Occupy Wall Street and Black Lives Matter,” Turney said.

Arizona Democratic state senator Martin Quezada, who has been pushing dark money disclosure legislation since last year, said his goal is to let voters know which special interests might have influence over a candidate.

“My bill in no way limits anyone’s free speech. It doesn’t say they can’t spend that money. They’re free to spend that money all they want. It only requires that if you’re going to spend that money, you have to tell us who you are,” Quezada said.

The CAP memo also warns activists to snuff out a burgeoning alliance in some states between liberal groups seeking more disclosure and Tea Party-like conservatives who often oppose the Republican establishment. “The Left has turned the transparency concept on its head to dupe conservative legislators and well-meaning Tea Party groups to help advance their initiatives,” the memo said, citing a 2014 Tallahassee voter campaign finance initiative that capped contributions in city races at $250 and established an ethics office.

“Transparency is for government,” the group reminded conservative activists. “Privacy is for people.”

Dan Backer, a lawyer who signed the CAP memo, said the group’s organizing should be a warning to advocates of stricter campaign finance rules that his side will use “a variety of means” including litigation to preserve the privacy of donors. Backer helped bring the 2014 McCutcheon case in which the U.S. Supreme Court removed aggregate limits on direct contributions, which along with the 2010 Citizens United decision set the stage for a new flood of money into politics.