Oil and gas companies -- with their broad spectrum of interests in Washington, D.C. -- tend to steer clear of brawls over presidential appointments. Presidents are usually able to fill high-level positions, even during periods of intense partisanship. Still, political and energy analysts say this year could bring some surprises during the confirmation process, including push-back from the oil and gas industry. There are oil and gas-related issues to consider, particularly the regulation of hydraulic fracturing. Then there is this: global warming, a U.S. environmental policy issue that, for the most part, multinational oil companies have ducked for the past two decades.