This ad from Mitt Romney shows why it’s difficult for an incumbent to win reelection with unemployment above 9 percent:

Note what Romney isn’t saying: anything about himself. You could watch that ad and entirely miss the fact that some guy named Mitt Romney is running for president — and it’s all the more effective for that. What Romney is signaling here is that he understands what the GOP’s general-election campaign against Obama will have to look like, and he’s capable of carrying it out.

There’s a lot of focus on candidate quality on the Republican side, but Republicans don’t need to run a candidate so much as they need to run the economy. Indeed, the party’s “best” candidate is likely the one best able to get out of the way and let the economy run their campaign for them. Which is why the best political advice Obama is likely to get is coming from his former economic adviser, Larry Summers, who warns:

The greatest threat to the nation’s creditworthiness is a sustained period of slow growth that, as in southern Europe, causes debt-to-GDP ratios to soar. Discussions about medium-term measures to restrain spending and raise revenue need to be coupled with a focus on near-term growth. Without the payroll tax cuts and unemployment insurance negotiated by the president and Congress last fall, we might well be looking at the possibility of a double-dip recession. Substantial withdrawal of fiscal support for demand at the end of 2011 would be premature. Fiscal support should, in fact, be expanded by providing the payroll tax cut to employers as well as employees. Raising the share of the payroll tax cut from 2 percent to 3 percent would be desirable as well. At a near-term cost of a little more than $200 billion, these measures offer the prospect of significant improvement in economic performance over the next few years translating into significant increases in the tax base and reductions in necessary government outlays.

This election will be won or lost by governance and the economy, not by candidates and campaigns. Another $200 billion in economic stimulus will mean a lot more to Obama’s reelection effort than $200 million in ads.