WASHINGTON — President Obama said Sunday that he understands the frustration of voters who want to see Washington work again, and he would start by taking his long-promised executive action to change immigration laws despite objections from Republicans in Congress.

The president also promised staff changes at the White House and remained optimistic that his remaining two years in office – with a Republican-controlled Congress installed by voters in the midterm elections – would provide an opportunity to continue pursuing the hope-and-change message that first ushered him into the presidency.

“I’ve got to make this city work better,” Obama told CBS in a wide-ranging Oval Office interview on “Face the Nation.”

The president acknowledged the Democratic Party’s sweeping election losses last week, which many in the party blamed on Obama’s low approval rating. “The buck stops here – with me, the buck stops right here, at my desk,” he said. “I’ve got to take responsibility for it.”

However, Obama also suggested that Republicans, who will control both the House and Senate in the new year, have been “really stubborn” opponents, and he doubled down on his promise to deliver immigration reforms where House Speaker John A. Boehner and Republicans had failed.

Polls show a large majority of Americans want Congress to pass immigration reform.

Obama plans to use his executive authority to enable as many as 5 million immigrants to remain in the U.S. without fear of deportation, many of them likely to be parents of American citizens. Action is expected by the end of the year.

Boehner and Sen. Mitch McConnell of Kentucky, the Republican leader, have warned that such a move would “poison the well” for the two sides as Republicans take control in the new Congress. But Obama said in the interview that aired Sunday that Republicans could easily undo his action by passing their own legislation on immigration.

“Their time hasn’t run out,” Obama said. “If in fact a bill gets passed, nobody’s going to be happier than me to sign it.”

“They have the ability, the authority, the control to supersede anything I do through my executive authority,” Obama said. “Nobody’s stopping them.”

Obama also said his decision to send 1,500 more U.S. troops to Iraq is a chance to help the Iraqi Army go on offense against the Islamic State, beyond what can be accomplished with the U.S.-led campaign of airstrikes.

And the president did not rule out sending more U.S. troops to the region, if needed. “I’m never going to say ‘never,’ ” he said.