Politics were on display early into Tuesday's budget hearing before the Senate Finance Committee, after Sen. Jim Bunning (R-Ky.) requested Treasury Secretary Tim Geithner deliver his entire testimony under oath.

Bunning's move could have subjected Geithner to later accusations of perjury, provided lawmakers could prove the secretary knowingly deceived the committee or misrepresented the budget. Perhaps sensing this, committee Chairman Max Baucus (D-Mont.) quickly shot Bunning's request down.

That prompted the Kentucky Republican to press Baucus to explain his reasoning.

"There are many reasons," Baucus replied. "One is that there is no Senate rule, or no committee rule, on this subject."

Baucus later added we "rarely require witnesses to testify under oath," noting that procedure is typically reserved for investigative or confirmation hearings.

[UPDATE, 11:20 a.m.] It seems Bunning's target was not so much the budget, but Geithner's role in the bailout of AIG. 

The two have long sparred over the New York Federal Reserve's role in orchestrating the purchase of AIG assets, and Bunning is among a number of lawmakers who has previously called on Geithner to resign his post.

The senator continued his line of attack Tuesday morning, again pressing the secretary to explain why the federal government ultimately bailed out a company whose risky behaviors almost prompted its demise.

Geithner replied by stressing AIG's dissolution would have been "catastrophic" to the U.S. economy, adding he and his colleagues took the course that was "the best way to contain damage at the least cost to the taxpayer."

"No one would ever want to be in that position ever," continued Geithner, growing frustrated with Bunning's questioning. He later noted the Fed would have "jumped on that and embraced" any other, less-costly solution, should one have been present upon AIG's collapse in 2008.