U.S. President Barack Obama on Wednesday defended the government\'s move to delay the approval process of a proposed oil pipeline between Canada and the United States.Appearing at a joint press conference with Canadian Prime Minister Stephen Harper after their meeting at the White House, Obama said it is important for the U.S. to examine the project \"rigorously,\" and the project\'s environmental impact must be \"properly understood.\"U.S. State Department last month delayed potential approval of the Keystone XL pipeline until 2013, falling after the presidential election due to intense opposition from environmentalists as well as public officials in the United States.The 7-billion-U.S.-dollar pipeline proposed by TransCanada, an energy giant based Canada, would run 1,700 miles (2,720 km) to connect Canada\'s oil sands to refineries around Houston and the Gulf of Mexico.\"We\'ve seen Democrats and Republicans express concerns about it. And it is my job as president of the United States to make sure that a process is followed that examines all the options,\" said Obama.There are no political considerations for the administration\'s delay of a decision on the pipeline until early 2013, insisted the president, who is seeking reelection next year.Republicans are pressing Obama to accelerate the project, saying the pipeline could significantly reduce U.S. dependence on Middle Eastern oil while providing thousands of jobs.Meanwhile, Republican leaders are also mulling including accelerated approval of the pipeline in legislation extending a payroll tax cut that is set to expire on January. 1.However, Obama opposed linking the pipeline to payroll tax cut, saying it should not be held hostage by any other issue and he would reject any such effort by congressional Republicans.