Ponnuru mentioned PolitiFact's role in fact checking the effects of the stimulus in the same context:
Media fact-check organizations have no such doubts. Factcheck.org says it’s “just false” to deny that the stimulus has created jobs. It cites the Congressional Budget Office’s estimate that the stimulus had saved or created millions of jobs. But the CBO, as its director has explained, hasn’t really checked the effect of the stimulus. It has merely reported what the results of additional federal spending and tax credits would be if you assume that spending and tax credits are stimulative.Ponnuru's column foreshadows the difficulty for the GOP in the coming election. The mainstream media will defend liberal orthodoxy on issues like the effects of the stimulus and health care bills.
In other words: If you assume that stimulus works, it must have worked. This circularity doesn’t bother PolitiFact, a group that seeks to elevate the tone of political debates but usually lowers it. It says people who deny the effectiveness have their “pants on fire.”