WASHINGTON – With Congress pushing back against his proposals for energy, taxes and other matters, President Barack Obama is taking a bend-but-don’t-break posture.

He will compromise on certain details if he must, he signaled at his news conference Tuesday evening, but not on the heart of his key initiatives.

His strategic retreats are a nod to political reality. He is angling to avoid confrontations he probably can’t win, but to sacrifice no more than is absolutely necessary.

On energy, for instance, influential Democratic lawmakers have joined Republicans in opposing Obama’s bid to reduce greenhouse gases through a program that would let companies buy and sell a limited number of permits to pollute.

“When it comes to cap and trade,” the president said, using the proposal’s nickname, “the broader principle is that we’ve got to move to a new energy era. And that means moving away from polluting energy sources towards cleaner energy sources.”

“I think cap and trade is the best way,” Obama said, but he stopped well short of insisting on it.

He did not retreat on contentious issues on which he holds the upper hand. Lifting a federal ban on embryonic stem cell research, he said, was the “right thing to do” despite criticisms from various quarters. Asked why he hasn’t asked Americans to do more to weather the economic crisis, he said, “I think folks are sacrificing left and right.”

Obama was less certain and dismissive on topics in which he faces potentially bruising battles with Congress. For example, he minimized a Senate leader’s proposal to end Obama’s signature tax cut for most working families after 2010.

“When it comes to the middle-class tax cut,” the president said, “we know that that’s going to be in place for at least the next two years.”

“If Congress has better ideas in terms of how to pay for it, then we’re happy to listen,” he said.

Obama said the main thrust of his massive budget proposal is moving the nation in the right direction to turn around the ailing economy. “This budget is inseparable from this recovery,” he said, “because it is what lays the foundation for a secure and lasting prosperity.”

He said he expects “serious efforts at health care reform,” but not lawmakers’ approval of every proposal in his $3.6 trillion budget. “We never expected, when we printed out our budget, that they would simply Xerox it and vote on it,” he said.

Obama used the 55-minute news conference’s last question, on Middle East peace efforts, to summarize his strategy of pressing his main goals while letting critics nibble at the margins if they must.

“When it comes to domestic affairs,” he said, “if we keep on working at it, if we acknowledge that we make mistakes sometimes, and that we don’t always have the right answer, and we’re inheriting very knotty problems, that we can pass health care, we can find better solutions to our energy challenges, we can teach our children more effectively, we can deal with a very real budget crisis that is not fully dealt with in my — in my budget at this point, but makes progress.”

The closest he came to smugness was in noting that once-fierce criticism of Treasury Secretary Timothy Geithner has abated this week.

“It was just a few days ago or weeks ago where people were certain that Secretary Geithner couldn’t deliver a plan,” Obama said of proposals to bail out the financial sector. “Today, the headlines all look like, ‘Well, all right, there’s a plan.’ And I’m sure there will be more criticism, and we’ll have to make more adjustments, but we’re moving in the right direction.”

Obama’s bend-not-break strategy will get a test Wednesday, when he travels to the Capitol to meet privately with Senate Democrats. Some of them are his most troubling critics on energy, health care, taxes and spending.