WASHINGTON, D.C. Teachers union president Randi Weingarten and Chancellor Joel Klein agreed yesterday that this week’s surprise state Senate flip leaves the fate of mayoral control up in the air. Weingarten and Klein made the remarks at a roundtable discussion here in Washington, D.C., that I attended.

Klein said the problem with the Republican coup is the possible gridlock it creates. If Senate Democrats challenge the GOP takeover in court, an ensuing legal battle could prevent any legislation from passing, Klein said. And if the legal battle dragged on through June 30, the date at which the current school law sunsets, that would send the city schools back to their pre-2002 structure — a situation many of the fiercest critics of the law have said they do not want.

Klein’s uneasiness with this week’s takeover challenges the argument that a Republican Senate is a boon to the effort to renew mayoral control. “Uncertainty is a bad thing,” Klein said.

For her part, Weingarten said that two days ago she would have predicted a reasonable compromise on a mayoral control law by the end of the month. But she said that the news from the Senate upended her confidence.

The roundtable discussion was organized by the journal Democracy, and it also included D.C. Schools Chancellor Michelle Rhee and Peter Edelman, of the Georgetown Law Center and a signatory of the Broader, Bolder statement on how to improve American schools.