President Barack Obama is warning Republicans that he will veto legislation passed by the GOP-led Congress if it rolls back his policies on health care, environmental regulations and other signature measures.

"I haven't used the veto pen very often since I've been in office, partly because legislation that I objected to was typically blocked in the Senate even after Republicans took over the House," he said in an interview with National Public Radio. "Now I suspect there are going to be some times where I've got to pull that pen out. And I'm going to defend gains that we've made in health care; I'm going to defend gains that we've made on environment and clean air and clean water."

Obama has only vetoed two bills during his tenure as president. But he is likely to use the veto pen much more frequently as Republicans gain control of the Senate, where outgoing Majority Leader Harry Reid had served as a Democratic buffer between the GOP-led House and the White House.

Obama told NPR host Steve Inskeep that the GOP victories in November mean that Americans will be looking for governance - not gridlock - from the party in control on Capitol Hill.

"Now you've got Republicans in a position where it's not enough for them simply to grind the wheels of Congress to a halt and then blame me," he said. "They are going to be in a position in which they have to show that they can responsibly govern, given that they have significant majorities in both chambers."

- Carrie Dann