We're on the hunt for the mystery senator (or senators) holding up approval of John Holdren and Jane Lubchenco, President Obama's nominees to become chief White House science adviser and head of the National Oceanic and Atmospheric Administration (NOAA).

To bring folks up to speed, it appeared initially that Sen. Robert Menendez (D-NJ) was the sole lawmaker standing in the nominees' way, thanks to an unrelated dispute with Democratic leaders over the Cuban trade embargo. But that obstacle is no longer operative, leaving the situation murky as Commerce Committee Chairman Jay Rockefeller (D-WV) references multiple holds on the nominees.

Yesterday we ruled out two GOP suspects, Sens. David Vitter (LA) and Mel Martinez (FL). Today we can strike two more likely suspects from the list: Sens. Jim Inhofe (R-OK) and John Barrasso (R-WY) both strongly oppose Holdren's pro-regulation stance on climate change, but both told me they're not behind the holds.

Inhofe couldn't confirm that the holds weren't coming from his environment committee, but he said flat out: "It's not me, though."