(CNN) -- "Follow the money" was a classic line from a classic movie about US politics. The film was "All The President's Men" -- the story of Watergate.
We don't know if anyone ever really uttered that phrase in the course of the break-in and cover-up that eventually brought down Richard Nixon. It was apparently a screenwriter's dramatic flourish. But it's still very good advice.
So follow the money in the US presidential election. It's going to two men who boast of their reputations as reformers. But it may also undermine a real post-Watergate effort to clean up corruption.
That's more than half a billion so far and the real presidential campaign is just starting.
Right after Watergate, the US set out to limit the money in politics and the influence it buys.
The law is are full of loopholes and widely considered in need of a new overhaul. But no one has ever turned down the $85 million.
This year? McCain has worked to clean up campaign fundraising and Obama has been running as an enemy of special interests and a candidate of 'change.' Both seem like the kind of men who would sign up fast.
But Obama has raised more money than any primary candidate in US history and owes his victory over Clinton, in part, to massively outspending spending her on television ads.
Experts believe that if he refuses the $85 million in public financing, he could raise hundreds of millions on his own. Obama is wavering.
Even McCain, who's had trouble raising really big money, doesn't want to agree to a financial handicap that could potentially cost him the election. If Obama rejects the deal, he says he could too.
So two men perceived as reformers may end-up undermining one of the most important reforms in US politics. Winning elections is about more than being high-minded. It's about being well-funded.
And if you want to know what a candidate will do to win, follow the money.