When Janet Yellen testifies Thursday before the Joint Economic Committee of Congress, all eyes will be on . . . well, it may not be Senator Cruz, who is likely going to be absent. Ordinarily he’d be the man for whom to watch, because it was he who injected the question of monetary policy into the Republican primary campaign. That happened in October at the CNBC debate in Boulder, where Rick Santelli asked Mr. Cruz about the Federal Reserve. Mr. Cruz called for passage of Audit the Fed and the establishment of a monetary commission to look at a system to apply rules to the Fed — and, ideally, he said, tying the dollar to gold.

That demarche had an astonishing effect. In Boulder, Senator Rand Paul promptly reminded everyone, and deservedly so, that Audit the Fed was his bill (even better, it was one of his father’s causes). Then came the GOP’s Fox News debate at Milwaukee, where the Republican candidates almost to a man and to one degree or another signed on to monetary reform. The reason for this is growing suspicions that policy errors by the Federal Reserve account for the weakness and joblessness of the Obama recovery. Monetary policy, we’ve long maintained, could be the most explosive issue of the campaign.

It’s not just the debates that have thrown this hearing into such sharp relief. There is also the Fed Oversight Reform and Modernization Act, which the House passed November 19 despite a last minute warning against doing so send to the new Speaker, Paul Ryan, and the minority leader, Nancy Pelosi, by Mrs. Yellen herself. The bill now goes to the Senate, which makes the Joint Economic Committee, which contains both senators and representatives, a kind of catbird seat. And what a committee of catbirds — not only Mr. Cruz, if he’s not out campaigning, but also Mike Lee of Utah and Thos. Cotton of Arkansas.

Not to suggest that Mrs. Yellen is the cat. On the contrary, the etymology of the word catbird does not refer to its prey but to its wonderful meowing and purring. Not a bad strategy for the GOP senators as they open up this most magnificent of issues. There are so many threads of it. The Krugmanites of the world, just to mark one of them, like to palm off the idea that all that animates the movement for monetary reform is the fear of inflation. They like to think that makes the monetary reform movement ridiculous, because the Consumer Price Index isn’t signaling inflation.

The movement for monetary reform, though, is not only about stable prices. It’s also about creating the conditions for economic growth and private-sector job creation. That is what the Senate is going to be looking at when it gets into the FORM Act. And that is on what the GOP candidates will be smart to focus. All of which is to say that we look forward to Mrs. Yellen’s appearance Thursday before the Joint Economic Committee, no matter who will be questioning her. She’ll be appearing before the branch of the government to which the Constitution grants every one of the monetary powers that are so central to our politics.