Presidential politics has always been a rich man’s game. But now, thanks to the Supreme Court ruling in Citizens United that upended decades of limits on campaign donations, financing a presidential race is the exclusive domain of the kind of megadonor whose portfolios make Mitt Romney look middle-class. ‘I have lots of money, and can give it legally now,’ Texas billionaire and top GOP moneyman Harold Simmons recently bragged to The Wall Street Journal. ‘Just never to Democrats.’

In past elections, big donors like Simmons gave millions for advocacy groups like Swift Boat Veterans for Truth. By law, such groups were only allowed to run issue ads – but instead they directly targeted John Kerry, drawing big fines from the Federal Elections Commission. Now, with the blessing of the Supreme Court, the wealthy can legally hand out unlimited sums to groups that openly campaign for a candidate, knowing that their ‘dark money’ donations will be kept entirely secret. The billionaire Koch brothers, for instance, have reportedly pledged $60 million to defeat President Obama this year – but their off-the-book contributions don’t appear in any FEC filings.

Even more money from megadonors is flowing into newly created Super PACs, which, unlike advocacy groups, […]