As President Obama remakes his senior staff, he is also shaping a new approach for the second half of his term: to advance his agenda through executive actions he can take on his own, rather than pushing plans through an increasingly hostile Congress.

A flurry of staff departures and promotions is playing out as the White House ends a nearly two-year period of intense legislative activity. Where the original staff was built to give Obama maximum clout in Congress, the new White House team won't need the same leverage with lawmakers.

"It's fair to say that the next phase is going to be less about legislative action than it is about managing the change that we've brought," White House senior advisor David Axelrod said in an interview.

Rahm Emanuel, a former member of Congress who helped establish the Democratic majority in the House, resigned last week as White House chief of staff. His successor, for now, is Pete Rouse, a former congressional aide who has never held elective office.

Rouse won't emulate Emanuel, who was able to negotiate with lawmakers as a peer. Instead, the interim chief of staff will have a more operational role.

Winning passage of legislation wasn't easy for Obama, even with Democrats in firm control of both houses of Congress. Conditions will get tougher if, as expected, the Republicans pick up seats in the midterm election next month, or possibly take control of Congress.

"Whether or not the Republicans take over majorities in one or both houses, the margins will be so much narrower that the strategy of putting together a Democratic bill and picking off a handful of Republicans to push it over the top won't be viable anymore," said William Galston, senior fellow at the Brookings Institution.

So the best arena for Obama to execute his plans may be his own branch of government. That means more executive orders, more use of the bully pulpit, and more deployment of his ample regulatory powers and the wide-ranging rulemaking authority of his Cabinet members.

"This would fit into the status quo for the White House," said Brad Dayspring, a spokesman for House Republican whip Eric Cantor of Virginia. "The White House is showing no effort to work with Republicans. It has shown no interest in listening to the American people and has at all costs tried to ram through legislation that was tremendously unpopular."

With healthcare and financial regulatory packages passed, the Obama administration is now focused on putting the measures in place, which could change the way Americans get medical treatment, take out mortgages and deal with banks and credit card companies.

One area of likely administration action is climate change. Legislation curbing emissions that cause global warming is stalled in Congress. Such efforts have a goal of reducing greenhouse gas emissions to 17% below 2005 levels over the next decade.

The Obama administration does not think it can achieve the same reductions through regulation alone. Nonetheless, the Environmental Protection Agency is determined to use its regulatory power under the Clean Air Act to begin lowering emissions, in the absence of congressional action.

"The ambition is to get a reasonable start," an Obama administration official said on condition of anonymity because he was not authorized to speak publicly.

A major effort is also underway to set up the regulatory apparatus aimed at preventing another collapse of the financial system. Regulators are drafting hundreds of new rules required by the recently enacted financial overhaul, such as subjecting bank holding companies and other institutions to stricter regulation.

As part of the effort, Elizabeth Warren, a prominent consumer advocate, also is helping to create a new agency meant to protect consumers from high-interest mortgages they can't afford, among other things.

The president's staff said an array of personnel changes had been under consideration for months. Rouse has been reviewing the staff organization since before Chicago Mayor Richard M. Daley announced he would not run for reelection, setting in motion Emanuel's exit.

Rouse's assessment assumed there would be a change in the White House relationship with Capitol Hill, even if the Democrats retain control of the House and Senate, officials said.

Although some Democratic strategists said Obama could use the fresh perspective than an outsider would bring, the White House seems to be going another route, promoting trusted aides and filling vacant positions internally.

Rouse, for instance, has spent months at Emanuel's elbow, preparing for the likely moment when he would be called on to step into the position.

In Christina Romer, the White House lost a prominent and candid economist who had helped sell the president's policies on Capitol Hill and through the media. When she left her post as chair of the Council of Economic Advisors, Obama had someone sitting nearby ready to take her place: Austan Goolsbee, a Chicago economist who worked side by side with Romer for 20 months.

Similarly, when Press Secretary Robert Gibbs moves on to another position, deputy Bill Burton is standing by, ready to take over.

Many in the West Wing assume that Burton, an Obama veteran who is the only person ever to stand in for Gibbs at media briefings, will become the country's first African American White House press secretary.

peter.nicholas@latimes.com

cparsons@latimes.com