WASHINGTON — Early in the Obama administration, a lobbyist for the Illinois-based energy producer Exelon Corporation proudly called it “the president’s utility.” And it was not just because it delivers power to Barack Obama’s Hyde Park neighborhood in Chicago.

Exelon’s top executives were early and frequent supporters of Mr. Obama as he rose from the Illinois State Senate to the White House. John W. Rogers Jr., a friend of the president’s and one of his top fund-raisers, is an Exelon board member. David Axelrod, Mr. Obama’s longtime political strategist, once worked as an Exelon consultant, and Rahm Emanuel, the Chicago mayor and Mr. Obama’s former chief of staff, helped create the company through a corporate merger in 2000 while working as an investment banker.

With energy an increasingly pivotal issue for the Obama White House, a review of Exelon’s relationship with the administration shows how familiarity has helped foster access at the upper reaches of government and how, in some cases, the outcome has been favorable for Exelon.

White House records show that Exelon executives were able to secure an unusually large number of meetings with top administration officials at key moments in the consideration of environmental regulations that have been drafted in a way that hurt Exelon’s competitors, but curb the high cost of compliance for Exelon and its industry allies.