Rep. Darrell Issa (R-Calif.) said in a letter to the Ford Motor Company on Thursday that he was "deeply concerned about undue political pressure exerted by the White House."The House Oversight Committee chairman's letter comes on the heels of reports earlier this week that the company had pulled an ad critical of the auto bailout following a phone call with administration officials.Ford denied Tuesday that the ad was removed because of political pressure, saying instead that it had simply been taken out of their ad rotation as scheduled."For those asking, the ad ran as part of a planned rotation and continues to run online. It contains the unscripted comments of a Ford owner. We supported emergency government support for our competitors and continue to support the decisions we made," Ford said in a statement posted to their Facebook page.But Daniel Howes, a conservative columnist for The Detroit News, said that the advertisement was pulled "in response to White House questions."In the ad, a man is asked why "buying American" was important to him when choosing a Ford pickup.“I wasn’t going to buy another car that was bailed out by our government. I was going to buy from a manufacturer that’s standing on their own: win, lose or draw," he responds. "That’s what America is about, taking the chance to succeed and understanding when you fail that you gotta’ pick yourself up and go back to work. Ford is that company for me."The auto bailout, which primarily benefited Ford competitors Chrysler and GM, was a cornerstone of the president's stimulus plan and supported by Ford. But conservatives have been increasingly critical of the auto bailout and stimulus as a whole as unemployment continues to lag.In the letter to Ford, Issa asks for a full explanation of the company's decision to pull the advertisement and whether any current or former employee of the Obama administration, United Auto Workers, or Democratic Party contacted the company about the ad. Issa also asks whether the company temporarily pulled the ad from its YouTube page."Given the close relationship between American automobile manufacturers, workers unions and the U.S. Government in the wake of a series of loans, grants, and stimulus programs, accusations of White House interference in private business matters to support its own political and policy agendas are very serious issues and warrant a full airing of the facts," Issa wrote.The White House has denied that it asked Ford to remove the ad, with White House Communications Director Dan Pfeiffer calling Howes's column "false."