Walter F. Roche Jr. and Michael A. Hiltzik:

What’s a politician to do upon discovery that a generous billionaire donor turns out to be a major tax dodger? It’s a dilemma already encountered by the Republican and Democratic parties in this season of unprecedented political fundraising.
At a time when newly powerful Democrats, including presidential hopeful Sen. Hillary Clinton of New York, are pressing for aggressive pursuit of unpaid tax bills to boost federal revenue, the party’s biggest financier and prominent Clinton backer is tied to one of the largest individual tax avoidance schemes on record.
And two Republican billionaires — Texas brothers who have poured a small fortune into supporting the presidential bids of two George Bushes and, more recently, Sen. John McCain (R-Ariz.) — were accused last year of exploiting offshore havens to escape taxes on nearly $200 million in gains.
Amid predictions that the 2008 presidential campaign will be the most expensive in history, with spending possibly topping $1 billion, pressure to raise huge sums of cash is a certainty. For candidates, the question is whether the headlong pursuit of deep pockets may also risk embarrassment over their donors’ financial baggage.
Sheila Krumholz, executive director of the Washington-based Center for Responsive Politics, said that candidates sometimes have to make their own “cost-benefit analysis.”