WASHINGTON (AP) — President Barack Obama said Wednesday that his administration has not done enough to combat global warming but said he hopes to begin his second term by opening a national "conversation" on climate change.

Obama said at a news conference that he took some steps in his first term to slow global warming, such as sharply increasing fuel efficiency standards for cars and trucks.

"But we haven't done as much as we need to," Obama said in his second comments on global warming since winning re-election last week.