HONOLULU - Bracing to do business with a Congress run solely by Republicans, President Obama is serving notice that he has no qualms about vetoing legislation he dislikes.

This would be a significant change in style for Obama come January, when the new Congress will be seated with the GOP in command not only in the House but the Senate as well. Obama has wielded the veto pen through his first nearly six years very sparingly. Since taking office in 2009, Obama has vetoed legislation only twice, both in fairly minor circumstances.

"I haven't used the veto pen very often since I've been in office," Obama said in an NPR interview airing Monday. "Now, I suspect, there are going to be some times where I've got to pull that pen out."

He added: "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's warning to the GOP that he would veto legislation if necessary to protect his agenda and laws like the Affordable Care Act came as he sought to set the tone for a year in which he and the Congress are on a near-certain collision course.

Buoyed by gains in last month's midterm elections, Republicans are itching to use their new Senate majority to derail Obama's plans on immigration, climate change, and health care, among other issues.

To overturn Obama's veto, Republicans would need the votes of two-thirds of the House and Senate. The party's majorities in both chambers are not that large, so they would need to persuade some Democrats.

But Obama said he was hopeful that at least on some issues, that won't be necessary, because there's overlap between his interests and those of congressional Republicans. On that point, at least, he's in agreement with Sen. Mitch McConnell (R., Ky.), the incoming majority leader.

"Bipartisan jobs bills will see the light of day and will make it to the president's desk, and he'll have to make decisions about ideology versus creating jobs for the middle class," McConnell said in response to Obama's comments.

In the interview, recorded before he left Washington this month for his annual Hawaii vacation, the president also said:

Russian President Vladimir Putin, hailed as a "genius" by some this year, hasn't been "so smart" as sanctions his country faces are proving successful.

He isn't ruling out the possibility the U.S. could one day reopen an embassy in Iran. "I never say never," he said, but added that ties must be restored in steps.

The U.S. is less racially divided than it was when he took office, despite recent protests over police treatment of black people. He said he thinks the issue of race has surfaced in a healthy way.