Erstwhile presidential candidate Newt Gingrich officially suspended his campaign today after announcing he would do so last week, and among the handful of people he thanked by name were Sheldon and Miriam Adelson. The couple were by far the largest donors to the super PAC supporting Gingrich’s presidential bid, and their $25 million donations nearly single-handedly kept the Gingrich campaign alive in its last days.

GINGRICH: And of course, while they weren’t directly associated with the campaign, it would be impossible for me to be here and thank everybody without mentioning Sheldon and Miriam Adelson, who single-handedly came pretty close to matching Romney’s super PAC.

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Gingrich’s praise of the Adelsons, and admission of their importance in his campaign, underscores how super PACs have fundamentally changed the political landscape, allowing a single household to spend unlimited amounts of money to nearly “single-handedly” fund candidates.

But his comments may also raise some eyebrows, as super PACs are legally not allowed to coordinate with campaigns and should exist entirely independently of the campaign. Gingrich notes the casino mogul and his wife “weren’t directly associated with the campaign,” but his public gratitude underscore the porous rules governing campaign finance in the post-Citizens United era.

Gingrich did not endorse Romney during his speech, but is expected to sometime in the near future, as the presumed GOP nominee has vowed to help Gingrich retire his campaign debt.

Federal election law requires candidates to disclose not just the names and addresses of all donors contributing more than $200 to a candidate, but also (where possible) the donor’s employer and occupation. Of the more than 750 donations received by Richard Mourdock’s primary campaign for Indiana Senate to date, one stands out. Earl Pendleton Holt, whose three reported contributions to Mourdock total $1,000, identifies himself as a self-employed “slumlord.”

Holt’s candor — be it serious or self-deprecating — is refreshing. Indeed, he has listed the same occupation on contributions this cycle to Senate hopeful Ted Cruz (R-TX), Congressional hopeful and former Rep. Charles Djou (R-HI), and unsuccessful Presidential hopeful Rep. Michele Bachmann (R-MN). But the interests of scores of other donors to Mourdock’s campaign — and its “independent” supporters — may be less obvious.

Tuesday’s closely watched Indiana Senate Republican primary will not just determine whether six-term Sen. Dick Lugar or state Treasurer Mourdock will face Rep. Joe Donnelly (D) this November. It will also mean the end of a $4.4 million independent expenditure war between a wide array of Super PACs and 501(c)(4)s — the largest amount of any non-presidential race so far this cycle. Though Lugar’s campaign, at of the last reporting period, had outspent Mourdock’s $6.6 million to $2 million, Murdock’s haul fundraising is impressive for a primary challenger and the gap has been partially made up by the $2.6 million to $1.8 million advantage he’s enjoyed in outside group spending.

Among the biggest forces backing Mourdock:

• The Club for Growth — led by former Rep. Chris Chocola (R-IN), the Club’s 501(c)(4), traditional PAC, and its Club for Growth Action Super PAC have spent at least $1.6 million on ads backing Mourdock and blasting Lugar. The group calls Lugar a “R.I.N.O.” (Republican In Name Only) despite his 63 percent lifetime record of voting with the group’s anti-government agenda.
• FreedomWorks for America — former Rep. Dick Armey’s (R-TX) “astroturf” group has done mailings and run ads saying Lugar has “lost touch with Indiana values,” spending over $545,000.
• Gun rights groups — The National Rifle Association has spent more than $322,000 on independent expenditures, criticizing Lugar’s votes to confirm President Obama’s Supreme Court appointments. A trio of pro-gun political action committees have donated about $10,000 to Mourdock’s campaign.
• The financial sector — although Lugar voted against the Dodd-Frank Wall Street Reform bill, political action committees for banks and related interests contributed over $17,500 to Moudorck’s campaign and individuals listed as working in the industry kicked in another $35,000-plus.
• Wealthy investors — About $20,000 of Mourdock’s donations came from wealthy investors and investment management executives.
• Big polluters — Mourock, himself a former coal company executive, got $5,000 from Murray Energy’s PAC (representing the nation’s largest privately-owned coal company) and more than $18,000 in individual contributions from employees and executives at Murray and other coal, oil, and gas companies.

With one of the key pro-Lugar groups pulling its ads over the weekend, it is quite possible that the man tied with Sen. Orrin Hatch (R-UT) for the longest tenure of any current Senate Republican may see his political career ended by the man backed by those groups — and a self-described “slumlord.”