The Koch-backed measures to eviscerate Wisconsin's limits on money in elections and neuter the state's election watchdog hit a stumbling block in the state senate this week, with a handful of Republican senators expressing concern that the measures go too far.

So the Kochs are going on the offensive.

David Koch's Americans for Prosperity is up with ads targeting constituents of GOP Senators Rob Cowles of Green Bay, Luther Olsen of Ripon, Sheila Harsdorf of River Falls, and Jerry Petrowski of Marathon, who have expressed reservations about the measures. The ads portray the nonpartisan Government Accountability Board (GAB) as a cold war-era agency "silencing free speech" and "raiding conservative's (sic) homes." AFP Wisconsin's director Eric Bott also said the group would be mobilizing its activists this week. AFP is the only group registered to lobby in favor of dismantling the GAB.

Wisconsin Club for Growth also launched a robocall campaign on Tuesday, with a recording of the Club's director Eric O'Keefe urging the wavering senators' constituents to demand the senators vote "yes" on the bill.

Wisconsin Club for Growth and Scott Walker were part of a $20 million scheme during the recall elections to evade the state's campaign finance laws and disclosure requirements, prosecutors believed. The GAB assisted in that investigation, sparking a legal and media counter-assault from the Club, with O'Keefe as its most visible proponent. The Wisconsin Supreme Court, whose majority was elected to the bench with at least $10 million in spending from the Club and other groups under investigation, shut down an investigation into the scheme earlier this year.

The Club has previously coordinated with Walker to support his legislative agenda. In 2011, for example, the Club ran ads supporting Walker's controversial union-busting Act 10 just days after it was introduced, and targeting moderate Republicans who were wavering in their support.

Citizen Opposition Slowed Bills' Progress

The bills to gut campaign finance laws and dismantle the GAB passed the Assembly last week, and seemed destined to quickly pass the Republican-controlled Senate. Voters from both the Republican and Democratic parties oppose more secret money in elections by wide margins, however, and a barrage of phone calls from concerned citizens has helped slow the bill's progress.

Some Republicans may be seeing through the rhetoric from their party leaders.

Although Walker and right-wing outlets closely associated with the groups under investigation have tried to smear the GAB as a partisan agency that used aggressive techniques during the John Doe probe, these allegations don't stand up to scrutiny.

"The reasons given for doing away with the G.A.B. are based on inaccurate, incomplete and, in many cases, completely false assertions by the proponents of this legislation," wrote GAB director Kevin Kennedy in a letter to Sen. Leah Vukmir, a leading critic of the GAB. He also submitted a response to her claims about the agency. "This point-by-point refutation of those specific assertions demonstrates that while the GAB. is not perfect, it is clearly not the 'failed experiment' that some claim it to be."

Some senators may also be wary of dismantling a nonpartisan board of retired judges that they voted to create just a few years ago, and replacing it with a board of partisan appointees that has proven ineffective in the past.

And, although Assembly Speaker Robin Vos says that court decisions like Citizens United require that the legislature erode disclosure laws and sanction coordination with outside groups, legal experts have proven these claims false.

The Brennan Center for Justice recently sent a letter to legislators noting that the bill's most egregious provisions "are not required by any recent federal or state court case; in fact, SB292/AB387 would leave Wisconsin with far weaker transparency protections than those upheld by the U.S. Supreme Court in Citizens United v. FEC."

Senate leaders cancelled a floor session scheduled for Tuesday to try and wrangle their caucus. It remains to be seen whether the holdout Senators will yield to this Koch attack.

Common Cause, the League of Women Voters, the Wisconsin Democracy Campaign and others are urging calls to Wisconsin Senators; go here for more information.