It's an understatement to say that Sheldon Adelson is a major player in this presidential election, given that he's pledged to contribute $100 million to Mitt Romney's campaign over the course of the year. 

And he's got a major personal stake in the outcome: He stands to save $2 billion in taxes if Mitt Romney becomes president, according to a new report out today from the left-leaning Center for American Progress. That would "earn" him back his pledged contribution in less than a year.

The substance of the report is interesting enough, but the most interesting thing of all, in light of these details, may be that the Democrats and the Obama campaign in particular haven't made a bigger deal of Adelson to this point.

He is, after all, the very picture of influence-buying, a billionaire casino magnate who has made more money than any other American over the last three years, and who is under investigation for an international pay-to-play land deal.

It's an ugly picture: He’s been greasing up Republican presidential candidates by promising an unheard-of amount of campaign money to unabashedly advance his business interests, in addition to advancing his pet political causes, like opposition to a two-state solution in Israel and Palestine.

The 2008 Republican nominee, John McCain, said recently he was concerned about the flow of Adelson money into the contest. 

Yet Adelson is not a household name, or anything like it. He hasn't been the focus of sustained derision and villification by the left, the way George Soros has been on the right (or, for the matter, the way the Koch brothers have been on the left).

This, despite the fact that Adelson is involved in some seriously questionable-looking business abroad: The investigation he faces is for potential violations of the Foreign Corrupt Practices Act, which prohibits U.S. companies from using payments to influence foreign officials in ways that might benefit the company’s business. In a nutshell, Adelson is accused of directing senior members of his company to pay a lawmaker in the Chinese territory of Macau, to help remove legal and other obstacles blocking the company’s real estate transactions.

(In a rare, officially sanctioned direct attack earlier in the year, the Democratic Congressional Campaign Committee called on one Republican congressman to return “Chinese prostitution money” he received from Adelson, but swiftly retracted the attack and issued an abject apology, after receiving a letter from the billionaire’s attorney.)

Meanwhile, Adelson has spent far more money to influence this presidential election than anyone in the nation, having already written checks for at least $36 million, according to the Center for Responsive Politics. This includes $15 million to bankroll Newt Gingrich’s super PAC in the Republican primary, and $10 million to Romney’s super PAC.

In addition to super PACs, Adelson has said he would also donate to nonprofits not required to disclose his contributions, making his overall largesse difficult to measure. But he has reportedly told friends he would spend up to $100 million during this cycle to get Romney and favored congressional candidates elected.

He has a large interest in the outcome of the election, and not just in terms of tax breaks.

For one thing, Adelson has significant financial interest in China and is pushing Romney to fight to raise the value of the Chinese yuan against the dollar. His scheme reportedly works like this: When Chinese gamblers pour into Adelson’s casinos in Macau, they’re likely to play with the same amount of currency regardless of exchange rates, and if the yuan were higher against the dollar, they’d effectively be spending more in U.S. currency. Romney supports this policy.

For another, Adelson strongly opposes a proposed two-state solution in the Middle East, and has called the prime minister of Palestine a terrorist. Romney, as it turns out, has echoed some of Adelson’s views of Palestine in recent weeks.

So why haven't the Democrats done more to train attention on Adelson and his ties to Romney?

In part, it's because there's no bite-sized indictment of Adelson to point to. Despite being the subject of a wide-ranging criminal investigation and many investigative stories, Adelson has never actually been charged with anything. Romney isn't doing anything legally wrong by benefiting from Adelson's money or allowing him to be involved with the campaign, and Adelson is not a recognizable enough figure to mean much to average voters without further explanation.

Their reluctance to go after Adelson may also be related to his involvement with Israel. He's not a card-carrying member of the official pro-Israel lobbying group, American Israel Public Affairs Committee, and actually Adelson reduced his involvement with the group after it supported a 2008 congressional letter calling for increased economic aid to Palestine. But he is a major funder of the broader pro-Israel movement, raising the possibility that an attack on him could invite a response that, in an election season, the Obama campaign would rather avoid.

But the most critical reason the Democrats aren't making more of a concerted effort to direct attention to Adelson has to do with the Republican nominee himself.

Sometimes, when you're running a campaign, you find it difficult to define your opponent negatively. In these instances, you begin to dissect his associations to see if there’s someone with whom he’s affiliated that might suggest vulnerability. This is when donors and surrogates like Soros or the Koch brothers attract notoriety.

But Mitt Romney has made such bank-shot strategies unnecessary. The Obama campaign has already succeeded in painting him as a greedy, secretive, out-of-touch, Gordon Gecko-like outsourcer who likes to fire people.

Who needs a proxy villain named Sheldon Adelson if you're already running against Mr. Monopoly?

Blake Zeff is a former presidential campaign aide to Barack Obama and Hillary Clinton and a former aide to Chuck Schumer and Eric Schneiderman.