WASHINGTON (MarketWatch) -- Treasury Secretary Timothy Geithner rejected a request from a Republican lawmaker that he resign for his handling of the economy. In a heated exchange during a hearing of the Joint Economic Committee of Congress, Rep. Kevin Brady, Republican of Texas and the top House Republican on the panel, said Geithner had failed as the Obama administration's point-man on the economy. "Will you step down from your post,?" Brady asked. Geithner replied that he served at the pleasure of President Barack Obama. Geithner said he agreed "with almost nothing" that Brady had said.