By Sean Strub

California State Treasurer Jesse Unruh was right when he said, in 1966, "Money is the mother's milk of politics." Democracy requires campaigns and campaigns require money. There's no getting around it.

Unruh's observation came long before the Citizens United decision enabled a corrupting influence of massive secret "outside spending" by Super PACs and 501(c)4 organizations.

And, since the decision, there has been a growing difference between Democrats and Republicans in how this spending revolution is used in primary elections.

For Republicans, outside spending has tended to back insurgent candidates running against incumbents or their party's establishment. But for Democrats, outside spending has increasingly coalesced to support incumbent or establishment candidates against insurgents or Democrats deemed too independent.

In other words, Republican outside spending supports challenges to their status quo; Democratic outside spending protects the status quo from any loss of control or change sought by outsiders.

In 2012, Nebraska's current senior senator, Deb Fischer, was the outsider and longshot tea-party favorite. Her Super PAC spending helped her knock off Jon Bruning, the state's attorney general, in a GOP primary race that Bruning was initially expected to win in a cakewalk.

That same year, six-term Sen. Dick Lugar (R., Ind.) lost a primary to the tea party's Richard Mourdock thanks to millions in Super Pac spending.

This trend is seen on the national level as well, in Rick Santorum's campaign for president in 2012 and Ted Cruz's race this year. Neither was a favorite of the party establishment, and each was fueled by massive Super PAC spending.

The Democratic side is different. Consider former Congressman Joe Sestak's April 26 primary loss to Katie McGinty, Gov. Wolf's former chief of staff, in the campaign for Pennsylvania's U.S. Senate seat.

Sestak threatened the status quo because apparently he wasn't a "go along, get along" guy. His independent streak prompted the Democratic Senatorial Campaign Committee (DSCC) to recruit primary opposition against him, going through a long list of prospects before settling on McGinty.

The reasons for this search vary, from a lingering grudge for Sestak's defeat of the DSCC-backed Arlen Specter - the Republican turned Democrat - in the 2010 Senate primary to an unwillingness last year to accept campaign staff demanded by the DSCC.

Until a month before the primary, the McGinty and Sestak campaigns were on track to each raise and spend a bit over $2 million; Sestak had led consistently in the polls, sometimes by as much as 17 points.

Then in the weeks immediately before the primary, almost $5 million in outside money was spent in support of McGinty and against Sestak by the DSCC and their allied 501(c)4, EMILY's List.

Some ads were pro-McGinty; many others were negative, including one the Washington Post Fact Checker gave its top level of falsity: "four Pinocchios." Sestak supporters formed a Super PAC but only spent $1.2 million.

As a result, momentum in the last days shifted to McGinty, who won the Democratic primary by 10 points.

This phenomenon plays out on the federal level as well. Former Secretary of State Hillary Clinton, the establishment candidate, has benefited from more than $76 million from Super Pacs and outside funds; the insurgent, Sen. Bernie Sanders, less than $1 million.

Despite the differences in who gets support, one aspect is common to both parties: secrecy.

Republicans rely on the secrecy of a small group of anonymous donors, allowing wealthy individuals - with the explicit purpose of backing insurgent candidates - to win primaries with restive voters.

Democrats depend on the secrecy of a small group of party power brokers who coalesce donors' money - contributions of all sizes, much of it donated with the intent it would be used against Republicans, not independent Democrats - to elect candidates supportive of the establishment.

The secrecy permitted by Citizens United has led to a corrupting influence by hidden donors, and, on the Democratic side, "hidden" party power brokers who wield influence against Democratic candidates by using donors' money for a purpose other than originally stated.

In both cases, the citizens are mostly kept in the dark about who is influencing the election. But on the Democratic side, even donors are shielded from knowing the end to which their contributions are being used.

The entire process is just one more step in the loss of transparency and the informed citizenry that a democracy relies upon.

Sean Strub is a small-business owner in northeast Pennsylvania and former executive director of the Pennsylvania Democratic Committee.