During the Democratic National Convention last week, Chicago Mayor Rahm Emanuel performed a neat campaign pirouette. He "resigned" as co-manager of President Barack Obama's re-election campaign, and took on a fundraising role with the pro-Obama super PAC called Priorities USA Action.

The shift exploits a nicety of Federal Election Commission rules, which don't allow coordination between super PACs and candidates (wink, wink). But with close advisers like Emanuel moving between camps - and the same is true for Republican super PACs - this FEC distinction is a fig leaf.

Emanuel can now court big donors for ever-larger sums. As campaign co-manager, his wooing by necessity bumped up against the federal giving limits: $2,500 per election to a candidate or $30,800 a year to a national party committee.

Emanuel described his new role as having a lot of "one-on-one conversations," and The Washington Post reported on Wednesday that he had obtained a seven-figure commitment to donate to the super PAC.

Presidents and top aides have always courted wealthy donors, but the stakes are higher in this election because the dollar figures are so much bigger. The Center for Responsive Politics predicts that the 2012 election will involve spending of about $6 billion, compared with $5.4 billion in 2008.

What do you suppose mega-donors are going to want as a return on their investment? The whole idea of limiting donations to a campaign was to curb any one person's influence on government.

The Republican super PACs have been raising money far more effectively. The two leading GOP groups - American Crossroads, co-founded by Republican strategist Karl Rove, and Restore Our Future, which is specifically supporting Mitt Romney - had raised $137 million through July, compared with $47.5 million for three Democratic super PACs: Priorities USA Action, House Majority PAC and Majority PAC.

Emanuel told PBS interviewers on Wednesday night that he was not going to allow the Democrats to be out-matched in fundraising if he could prevent it. And that's the problem. This presidential campaign has morphed into a financial arms race, and both sides have little choice but to match each other warhead for warhead.

Of course, we may never know what big donors gain from government, because we may not know who those donors are. Super PACs must disclose donation amounts, but individuals can remain anonymous by setting up intermediary corporations. The Disclose Act would have required super PACs, unions and other groups to reveal names, and donations of $10,000 or more, within 24 hours, but Senate Republicans blocked that legislation in July.

Democrats had held the high ground on this issue, and Priorities USA Action has refused to accept anonymous donations. Obama himself, in an interview last month with the website Reddit.com, discussed mobilizing support for a constitutional amendment to overturn Citizens United, the 2009 Supreme Court decision that gave rise to super PACs. But until the game changes, Democrats appear resolved to play it as it lays. Obama made a similar call in 2008, when he opted out of public financing.

It's not realistic to expect either side to unilaterally disarm. But what if the candidates agreed to ask outside groups to limit expenditures? In the hotly contested Senate race in Massachusetts, Republican incumbent Scott Brown and Democrat Elizabeth Warren are doing this effectively. We're now in a presidential arms race; in the future, let's follow the arms-treaty model. The two sides can negotiate a pullback from mutually assured destruction.

I can't imagine that TV ads or even a few dozen fliers would sway my vote. I'd be more impressed by a presidential candidate who stood for sanity on campaign spending.

This essay was first published in Newsday.