In case you missed it, Treasury Secretary Timothy Geithner is under fire. Liberal netroots, including Daily Kos, are calling for him to step down. At least one group, Americans for Job Security, is running ads calling for Geithner — along with embattled Sen. Chris Dodd (D-Conn.) — to resign. His name is savaged on television every hour.

Most damaging, however, is the recent talk questioning Geithner's very competence. This puts Geithner, whose nomination was hailed by many Republicans and business groups, in an even tighter spot. As soon as his supporters argue Geithner is indeed competent, the argument is lost. It threatens to become a narrative that could weaken not only Geithner's tenure but that of the Obama administration.

One need look no further than the reaction of much of the public to the Bush administration's handling of Hurricane Katrina. Once voters began questioning the competency of FEMA and, by extension, the White House, changing the conversation — and the minds of voters who took that position — was impossible. When the issue of competency arises, the genie just won't go back into the bottle.

For now, the best Geithner can do is put his head down and focus on his role. Reaction to this morning's announcement on toxic bank assets — especially market reaction — is, as the New York Daily News noted, "a major test." In the meantime, Geithner can't afford any more major tests, questions of what he knew about AIG bonuses and when or Sen. Dodd grabbing him by the collar and throwing him under the bus again. These only add to the competency question.

President Obama is standing behind Geithner, saying publicly he would not accept Geithner's resignation should he offer it. That should be of little solace to Geithner — presidents are always 100 percent behind their staff. Until they're not.